bluuebunny/crossref_metadata_2025 huggingface dataset:
Self Organized Array of Quantum Nanostructures Via a Strain Induced Morphological Instability
Authors: Montiel David , Müller Judith , Poiré Eugenia Corvera
Published: April 2011

Motivated by the work of Li et al. [1], we have studied the strain induced morphological instability at the submonolayer coverage stage of heteroepitaxial growth on a vicinal substrate with regularly spaced steps. We have performed a linear stability analysis and determined for which conditions of coverage a flat front is unstable and for which conditions it is stable. For low coverages the instability will cause the front to break in an array of islands. Assuming that the fastest growing mode of the instability determines t he properties of the array, we make an estimation of the islands sizes and aspect ratios as well as an estimation of the separation length between islands of the array formed when the dominant mechanism for transport of matter is diffusion of particles along the growing front. These estimations are given as functions of the terrace width and coverage. Since these ones are experimentally controllable parameters, our results could be used to tailor the spontaneous formation of quantum nanostructures.
InP Self Assembled Quantum Dot Lasers Grown on GaAs Substrates by Metalorganic Chemical Vapor Deposition
Authors: Dupuis R. D. , Ryou J. H. , Heller R. D. , Walter G. , Kellogg D. A. , Holonyak N. , Reddy C. V. , Narayanamurti V. , Mathes D. T. , Hull R.
Published: April 2011

We describe the operation of lasers having active regions composed of InP self-assembled quantum dots embedded in In0.5Al0.3Ga0.2P grown on GaAs (100) substrates by MOCVD. InP quantum dots grown on In0.5Al0.3Ga0.2P have a high density on the order of about 1-2x10 cm-2 with a dominant size of about 10-15 nm for 7.5 ML growth.[1] These In0.5Al0.3Ga0.2P/InP quantum dots have previously been characterized by atomic-force microscopy, high-resolution transmission electron microscopy, and photoluminescence.[2] We report here the 300K operation of optically pumped red-emitting quantum dots using both double quantum-dot active regions and quantum-dot coupled with InGaP quantum-well active regions. Optically and electrically pumped 300K lasers have been obtained using this active region design; these lasers show improved operation compared to the lasers having QD-based active regions with threshold current densities as low as Jth ∼ 0.5 KA/cm2.
Shape Transitions of Self-Assembled Ge Islands on Si(001)
Authors: Rastelli Armando , Kummer Matthias , Känel Hans Von
Published: April 2011

Coherently strained Ge islands were grown at a substrate temperature of 550°C by magnetron sputter epitaxy on Si (001) and studied by scanning tunnelling microscopy (STM). The shape changes induced by exposure to a Si-flux at 450°C were investigated as a function of the Si-coverage. During Si-capping, multifaceted domes were found to flatten and to transform into {105}-faceted pyramids and subsequently into stepped mounds through intermediate shapes. The observed sequence of morphological changes is induced by Si-Ge intermixing and is shown to be the inverse of that occurring during Ge or Si1-xGex growth on Si (001). The results are interpreted with a model in which the stable shape of an island mainly depends on its volume and composition.
Morphology of Self-Assembled InAs Quantum Dots on GaAs(001).
Authors: Arciprete F. , Patella F. , Fanfoni M. , Nufris S. , Placidi E. , Schiumarini D. , Balzarotti A.
Published: April 2011

We have followed by Atomic Force Microscopy (AFM) the epitaxial growth of InAs on GaAs(001) starting from the initial formation of a strained two-dimensional wetting layer up to the self-assembled nucleation and growth of 3D nanoparticles. In this work we underline many aspects of the morphology of this system, which substantiate the role either of kinetics on thermodynamics in the process of growth as well as the role of surface instabilities in controlling lateral ordering of the nanoaggregates.
Optical Characterization of Self-Assembled Ge Dots on Silicon
Authors: Marabelli F. , Rastelli A. , Valsesia A. , Känel H.von
Published: April 2011

Self assembled quantum dots of Ge were obtained by magnetron sputter epitaxy of seven monolayers of Ge on a 33nm thick undoped Si buffer grown on top of a p-doped (100) Si substrate. The samples obtained in this manner were then capped with an increasing number of silicon layers in order to study the effect of Si deposition on the strain and the morphology of the dots. They were characterized “ex situ” by spectroscopic ellipsometry and Raman spectroscopy. The optical experiments revealed well defined differences between the capped and uncapped samples and among samples with different cap thicknesses.

By monitoring the energy and the splitting of the E0', E1 and E2 interband optical transitions of Ge and the Ge-Si vibrational mode, the optical measurements evidence strain effects as well as the formation of SiGe alloy, in agreement with the “in situ” STM measurements.
Self-Assembled Magnetic Dots, Antidots, Dot Chains, and Stripes: Epitaxial Co on Ru(0001)
Authors: Li Dongqi , Yu Chengtao
Published: April 2011

Lateral magnetic nanostructures have been grown via molecular beam epitaxy in ultrahigh vacuum and characterized ex-situ with atomic force and magnetic force microscopy. We observed that epitaxial growth of Co onto Ru(0001) at elevated temperature results in three-dimensional Co islands (dots) or a flat Co film network with deep holes (antidots) in truncated pyramidal shapes. The lateral size of these dots/antidots, in the order of 100 nm, tends to be uniform at each given coverage. We attribute the growth mode mainly to strain relaxation of Co epitaxy on Ru, which has a 8% lattice mismatch. In addition, we have explored the placement of these dots on a grooved Ru(0001) surface. The dots automatically align into linear chains along the asymmetric grooves to form either dot chains or continuous stripes, which would open new opportunities in creating either ordered magnetic arrays or arbitrary arrangements.
Magnetic Interactions in Fe Nanoparticle Arrays
Authors: Farrell D. , Yamamuro S. , Ijiri Yumi , Majetich S. A.
Published: April 2011

The preparation of monodisperse Fe nanoparticles and self-assembly into hcp and fcc or fcc-like arrays is described. Here dipolar interactions dominate for the interparticle spacings studied (1.4-3.4 nm). Comparison of the low temperature magnetic properties of multilayer arrays with those of dilute suspensions of the same particles show increased coercivity and slower magnetic relaxation in the arrays. Mean field calculations of magnetic interaction fields suggest the type of ordered structures formed.
Free-standing Smectic LC Elastomer Films
Authors: Tolksdorf C. , Zentel R. , Köhler R. , Dietrich U. , Lösche M. , Stannarius R.
Published: April 2011

We probe the mesophase transitions and layer structures in thin ordered smectic liquid crystalline elastomer films by means of x-ray diffraction and optical microscopy. Oriented elastomer films of submicrometer thickness are produced by crosslinking freely suspended smectic polymer films. After crosslinking, the mesomorphism is similar to that of the precursor polymer. Smectic layers align parallel to the film plane. The layer spacing increases with temperature in the SmC* phase while it decays above the SmC*-SmA transition.
Reactive Mesogenes: Synthesis and Application in Optoelectronic Devices
Authors: Strohriegl Peter , Hanft Doris , Jandke Markus , Pfeuffer Thomas
Published: April 2011

Reactive mesogenes posess polymerizable groups attached to a rigid, liquid crystalline core. From such molecules, densely crosslinked networks in which the liquid crystalline order is permanentely fixed can be formed by photopolymerization.

Our major synthetic goal was the formation of glass forming reactive mesogenes. Such compounds do not crystallize upon cooling but vitrify and form supercooled LC-phases ('LC-glasses'). They exhibit broad LC-phases and enable us to carry out photopolymerization in a broad range of temperatures.

We have systematically investigated how the topology of the reactive mesogenes influences the stability of the resulting glasses. Comparing twin molecules with three- and four-armed stars we found that the supercooled LC-phase in the three-armed stars has a stability superior to both twin molecules and four-armed stars. In the three-armed star Triple-4 with a suitable substituent pattern the supercooled LC-phase is stable at room temperature for at least nine months. Doped with suitable chiral molecules the glass forming nematics form cholesteric phases which were used for cholesteric polymer networks and for polarization holograms with one s-and one p-polarized writing beam.

Furthermore we have extended our synthetic efforts to reactive mesogenes with three or five conjugated fluorene units as LC-core. After orientation, the mesogenes were photocrosslinked and used as active layer in OLEDs that emit highly polarized blue light.
Tuning the Surface Properties of Elastomers Using Hydrocarbon-Based Mechanically Assembled Monolayers
Authors: Efimenko Kirill , Genzer Jan
Published: April 2011

We use static contact angle measurements and near-edge absorption fine structure to elucidate the surface structure and molecular orientation of hydrocarbon-based mechanically assembled monolayers (H-MAMs), structures formed by combination of assembly of alkyl moieties onto flexible elastomeric substrates and mechanical manipulation of the substrates. Specifically, we report that the organization of the grafted molecular array (“liquid”-like vs. solid-like) can be tailored by varying the degree of stretching of the elastomeric substrate. We also show that the H-MAM surfaces exhibit excellent stability.
Effect of Semiconductor and Dye Interfacial Properties in Dye-Sensitized Solar Cells
Authors: He Jin-An , Mosurkal Ravi , Kumar Jayant , Li Lian , Chittibabu K. G. , Samuelson Lynne A.
Published: April 2011

The back recombination processes of electrons from the semiconductor to the oxidized dye and the oxidized redox species can dramatically reduce the efficiency of conventional dyesensitized solar cells (DSSCs). In this work, we have used the electrostatic layer-by-layer (ELBL) assembly technique to specifically manipulate and control the interface between the semiconductor and adsorbed dye layers in DSSCs to potentially minimize this recombination behavior. The interfacial modification has been achieved by applying different combinations and thicknesses of polyelectrolytes using the ELBL method and the performance of the cells has been monitored by measuring the I-V characteristics and the efficiency of the solar cells. The results indicate that an ultrathin polyelectrolyte film, on the order of a few Angstroms, between the semiconductor and the dye layer plays a crucial role on the performance of the solar cell. More specifically, the efficiencies of the DSSCs do not show any improvement after the interfacial treatment when compared to untreated samples. Surprisingly, the efficiency of the cells decreases to some degree, depending on the thickness of the polyelectrolyte films. This suggests that incorporation of a thin (several Angstroms) passive layer between the semiconductor and dye layer in these devices results in an increased resistance of the device and do not significantly reduce the back electron recombination as was originally anticipated. These results show interesting mechanistic information regarding the interfacial interactions of semiconductor/dye interfaces in DSSCs.
Synthesis of TPD-Containing Polymer Thin Films by Physical Vapor Deposition
Authors: Usui Hiroaki , Yoshioka Terufumi , Katayama Takahiro , Tanaka Kuniaki , Sato Hisaya
Published: April 2011

Polymer thin films having tetraphenyl diaminobiphenyl (TPD) side chain were prepared by evaporating its acrylate monomer by the ionization-assisted deposition (IAD) method. IR absorption and GPC analyses showed that the electron irradiation to the evaporated material works efficiently to initiate the polymerization reaction on the substrate surface, while the simple evaporation produced films mainly consisting of the monomers. The reaction was enhanced by increasing the substrate temperature. However, the surface roughness increased with increasing substrate temperature. Post annealing can be an alternative method to enhance the polymer yield. Light emitting diodes were prepared by stacking the TPD polymer layer, Alq3 emissive layer, and Al electrode on ITO-coated glass. The IAD polymerization can be a useful method for preparing polymer thin films for organic optoelectronic devices.
Wafer Bonding Using Dielectric Polymer Thin Films in 3D Integration
Authors: Kwon Y. , Lu J.-Q. , Kraft R. P. , McDonald J. F. , Gutmann R.J. , Cale T. S.
Published: April 2011

A key process in our approach to monolithic three-dimensional (3D) integration is the bonding of 200-mm wafers using dielectric polymer thin films as bonding glues. After discussing the desired properties of polymer thin films, we describe how bonding protocols are evaluated using silicon and glass wafers. After bonding, the fraction of bonded area was inspected optically and a razor blade method was used to indicate bonding strength. Thermal stability and bonding integrity were evaluated using thermal cycling and backside grinding and polishing. To date, we have studied benzocyclobutene (BCB), Flare™, and methylsilsesquioxane (MSSQ) and Parylene-N as bonding glues. Wafer pairs bonded using BCB showed a larger fraction of bonded area, and those using Flare indicated higher thermal stability. Both BCB and Flare glues provided good bonding integrity after backside grinding tests. Changes in the chemical structures of BCB and Flare glue during bonding were analyzed using FTIR in order to understand the bonding mechanism and to improve the bonding process.
Dewetting of A Complex Polymer: Perfluoro-Ionomer
Authors: Hill Teresa A. , Jiao Xuesong , Martin Charles W. , Perahia Dvora
Published: April 2011

The stability and interfacial structure of ultra thin films of perfluoro-ion containing polymers (ionomers) have been studied using atomic force microscopy and neutron reflectometry. These complex polymers have significant technological applications from thin coatings, to fuel cells as polymer electrolyte membranes, to protective clothing. In particular we focused on the study of [(CF2CF2)n (CF2CFR)]m where R= [OCF2CF2SO3 (X)] and X=H, (800 equivalent weight), coated on silicon oxide. Neutron Reflectometry has shown that film consists of three distinct regions: a region of high density at the interface with the silicon oxide, an intermediate layer with constant density and an air-interface layer where the density decreases due to interfacial roughness. In contrast to noionic polymers, the films proven stable as a function of annealing time above the bulk glass transition, i.e the films do not dewet. This stability is attributed to electrostatic interactions.
Liquids Under Shear Explored by Neutron Scattering: A Problem in Lubrication
Authors: Wolff Max , Hock Rainer , Magerl Andreas , Frick Bernhard , Zabel Hartmut
Published: April 2011

Considering the atomic scattering cross sections for neutrons they are an excellent tool to investigate lubrication problems. Two different shear cells have been built to investigate both the dynamics and structural properties of liquids under shear: one cell has been optimised for quasielastic and inelastic neutron scattering while another one has been designed for reflectivity and diffraction work. The dynamical aspects have been studied on the high-resolution backscattering instrument (IN16 at Institut Laue-Langevin (ILL)). Data with a commercial motor oil as a sample have been taken in contact with an aluminium boundary showing directly the developing anisotropy of diffusion under shear. Furthermore within the same set-up it has been possible to monitor the macroscopic velocity distribution including surface slip. In addition, a diffraction experiment has been carried out, demonstrating from a measurement of the position and the profile of the graphite 002 reflection that the ordering of macroscopic graphite particles in a flowing liquid can be studied with neutrons and an ordering with a tilt angle of the particles of 5° to the flow has been determined.
Effect of Stationary Particles on the Phase Separation of Binary Fluids
Authors: Suppa Domenico , Kuksenok Olga , Balazs Anna C. , Yeomans J.M.
Published: April 2011

Phase separating binary fluids with the addition of immobile particles, which act as osmotic force centres, were simulated using a Lattice Boltzmann model in two dimensions. In the hydrodynamic over-damped limit, where the flow is entirely driven by capillary effects, the presence of particles that are preferentially wetted by one of the fluid components significantly affects the kinetics of the growth of the fluid domains. The late time dynamics is governed by the wetting interactions and the final size of the domains can be tailored by varying the strength of the particles-fluid interaction as well as the particles concentration. These features are predicted within a simple theoretical model and are amenable of experimental checks.
One- and Two-Particle Microrheology in Entangled Solutions of fd Virus
Authors: Addas Karim M. , Levine Alex J. , Tang Jay X. , Schmidt Christoph F.
Published: April 2011

We have used one- and two-particle microrheology, employing μm-sized beads and laser interferometric displacement detection, to study the rheological properties of entangled solutions of the filamentous fd virus. Thermal fluctuations of the embedded probes were measured and viscoelastic parameters of the embedding medium were derived. In two-particle microrheology the correlated motions of two identical particles separated by a varying distance in the medium are analyzed, which can avoid biased results due to surface-depletion effects near the probes.
No Need To Dry - Environmental Scanning Electron Microscopy Of Hydrated System
Authors: Donald Athene M
Published: April 2011

The environmental scanning electron microscope (ESEM) offers a new approach for the examination of biological samples at rather high resolution. It permits samples to be imaged without extensive specimen preparation, and specifically requires neither drying nor coating. This implies that organic samples can be looked at in their native state, without the danger of artefacts being introduced. A few specific examples both of static imaging, and also images obtained during dynamic mechanical testing are given in this article to illustrate the power of the technique.
Capillary Formation In Microfabricated Polymer Scaffolds
Authors: Borenstein Jeffrey T. , King Kevin R. , Terai Hidetomi , Vacanti Joseph P.
Published: April 2011

One of the primary challenges for engineering thick, complex tissues such as vital organs is the requirement for a vascular supply for nutrient and metabolite transfer. Earlier work has shown that Solid Freeform Fabrication techniques such as Three-Dimensional Printing (3DP) are capable of producing biodegradable scaffolds for the subsequent formation of a wide range of tissues and organs. While this approach shows great promise as a method for constructing complex tissues and organs in vitro, the resolution of the process is currently limited to length scales larger than the narrowest capillaries in the microcirculation. In this work, microfabrication technology is demonstrated as an approach for organizing endothelial cells in vitro at the size scale of the microcirculation. Standard process techniques utilized to build MEMS (MicroElectroMechanical Systems) devices include photolithography, silicon and glass micromachining, and polymer replica molding. Photolithography is used to print a model network of blood vessels on silicon wafers; the network is designed to replicate the fluid dynamics of the vasculature of a particular tissue or organ. A reverse image of the channel network is formed either by Deep Reactive Ion Etching (DRIE) of silicon or through the use of a thick negative-polarity photoresist (SU-8). Polymeric scaffolds are formed by replica molding, using the silicon wafer as a master mold. Microfluidic chambers have been constructed from PDMS and other biocompatible polymers. Initial cell seeding experiments demonstrate that rat lung endothelial cells attach in a single layer to the walls of these structures without occluding them, providing early evidence that MEMS process technology can serve as a method for organizing capillary networks.
Traction Stresses and Morphology of 3T3 Fibroblast Cells on Fibronectin-versus RGD- Modified Elastic Substrata
Authors: Rajagopalan Padmavathy , Marganski William A. , Dembo Micah , Wong Joyce
Published: April 2011

We report a study on cellular traction forces and morphology on fibronectin (FN)- and Arg-Gly-Asp (RGD) modified substrata. We have focused on fibronectin- and RGD- modified substrata because RGD is a primary cell-binding site on fibronectin. In this study we report the traction stresses exerted by NIH (National Institutes of Health) 3T3 fibroblasts on model polyacrylamide hydrogel substrates using the elastic substrata technique. At equal values of input concentration of fibronectin and RGD we find that the values forprojected cell area are similar. However, a significant difference is observed in the traction forces exerted by fibroblasts on fibronectin- compared to RGD-modified surfaces. At equal values of input concentration, the average force exerted by NIH 3T3 fibroblasts is approximately ten fold higher on fibronectin-modified surfaces in comparison to RGD-modified surfaces.
Effect of Sulfate Content of Biomacromolecules on the Crystallization of Calcium Carbonate
Authors: Arias José I. , Jure Carolina , Wiff Juan P. , Fernández María S. , Fuenzalida Víctor , Arias José L.
Published: April 2011

Natural composite bioceramics such as bone, teeth, carapaces and shells contain organic and inorganic moieties, with the organic matrix components directly involved in the precise formation of these structures. We have previously shown that chicken eggshell contains two main sulfated polymers (proteoglycans), referred to as mammillan and ovoglycan which are involved in nucleation and growth of the eggshell calcite crystals. They differ on their anionic properties due to the carboxylate and sulfate content of their glycosaminoglycan component. Based on biological and biochemical evidences, the putative role of mammillan, a keratan sulfate proteoglycan, is in the nucleation of the first calcite crystals, while that of ovoglycan, a dermatan sulfate proteoglycan, is to regulate the growth and orientation of the later forming crystals of the chicken eggshell. In this communication, a systematic study of the influence of variable concentrations of glycosaminoglycans differing in their sulfation status on the morphology, size and number of calcium carbonate crystals after crystallization on microbridges from a calcium chloride solution under an atmosphere of ammonium carbonate at different pH is presented. Depending on the pH and concentration, the variation of sulfation status drastically changed the morphology, size and number of calcite crystals. The produced calcite particles with various morphologies are promising candidates for some novel materials with desirable shape- and texture-depending properties.
Influence of Zinc on the Formation of Granules of Calcium Pyrophosphate
Authors: Masala Ombretta , O'Brien Paul
Published: April 2011

Accumulation of metals in inorganic granules is very common in invertebrates. The formation of metal deposits in both intra- and extracellular sites can be seen as a process for the detoxification of heavy metals. In barnacles, such inorganic granules usually contain calcium pyrophosphate. Incorporation of metals within such granules occurs mainly via the formation of metal pyrophosphate salts. In order to assess the chemistry of some reactions occurring during granule formation, the synthesis of calcium pyrophosphate, doped with zinc(II) ions with different [Zn]:[Ca] molar ratios, has been investigated at pH 7 and 25 °C. The thermal stability of the products was studied at different temperatures. Considerable variations occur in the structure of calcium pyrophosphate when zinc ions are present in solution in small concentrations.
Texturization Analysis by X-ray Diffraction of Shells of the MusselIschadium recurvum(Rafinesque, 1820) (Mollusca Bivalvia)
Authors: Gómez-Martínez Octavio , Aguilar Daniel H. , Alvarado-Gil Juan J. , Quintana Patricia , Aldana-Aranda Dalila
Published: April 2011

Most of the inorganic biomineralized materials are deposited on an organic matrix that controls the orientation and structure of the crystals. It is thought that chemical groups at the surface of the matrix may act as a template for the nucleation and growth of the mineral. A x-ray diffraction study of the texturization development of the bivalve mollusk shells is presented; specifically, the musselIschadium recurvum(Rafinesque, 1820), in different growing stages. The x-ray reflections show a preferred orientation that changes as the mollusk grows, and at the final stages only two crystallographic planes prevail.
Infrared Spectroscopy Characterization of Marine Shells
Authors: Gomez-Martinez Octavio , Aguilar Daniel H. , Quintana Patricia , Alvarado-Gil Juan J. , Aldana Dalila , Diaz-Flores Laura L. , Yañez-Limon Martin
Published: April 2011

Fourier Transform infrared spectroscopy has been employed to study the shells of two kind of mollusks, American oysters (Crassostrea virginica) and mussels (Ischadium recurvum). It is shown that it is possible to distinguish the different calcium carbonate lattice vibrations in each case, mussel shells present aragonite vibration frequencies, and the oyster shells present those corresponding to calcite. The superposition, shift and broadening of the infrared bands are discussed. Changes in the vibration modes due to successive thermal treatments are also reported.
The Incorporation of Laser Ablation for Sampling into a Proton X-ray Emission System
Authors: Abraham Meg , Northover Peter , Grime Geoff
Published: April 2011

The variation with depth of the composition of corrosion layers on buried metal objects can provide the archaeologist with valuable information relating to the burial conditions of the object. In some cases these layers can be very thick and so, normally destructive methods such as sampling are used to characterise the metal and corrosion layers when possible. We have developed a system for the use of a microfocused high power pulsed Nd:YAG laser to ablate the corrosion layer in a series of controlled steps while monitoring the composition of the exposed surface using focused PIXE and RBS in the external beam facility of the Oxford Scanning Proton Microprobe. With proper manipulation of the data we are able to calculate the values for trace elements at various depths in the corrosion layer. It is hoped that this system will lead to a better understanding of corrosion properties.
Extraction of Material from Oil Paints by Solvents
Authors: Erhardt David , Cunningham Roland H. , Räsänen Sirpa
Published: April 2011

Drying oils used to formulate oil paints consist primarily of polyunsaturated triglycerides, along with smaller amounts of mono- and diglycerides, free fatty acids, and other compounds such as sterols. The drying of oils occurs through an oxidative crosslinking process that also produces smaller scission products such as short chain fatty acids and diacids. Compounds that are not attached to the crosslinked oil matrix include glycerin, the unreactive free saturated fatty acids and their glycerides, soaps of fatty acids produced by reaction with metal ions from the pigment, and scission products. As the oil ages, additional soluble material is produced by hydrolysis of glyceride esters. These relatively low molecular weight compounds can be extracted by exposure to solvents, as occurs during the cleaning of paintings. Excessive extraction of material canembrittle the paint film and affect the appearance of the paint. This paper examines the types and amounts of compounds extracted from oil paint films as a function of solvent, exposure time, pigment, and age of the paint. The results indicate that solvents vary more in the speed that they extract material than in their selectivity. The composition of the extracts is consistent with predictions based on the mechanisms of the drying and aging processes. These results confirm the importance of using the least polar solvent possible to clean paintings and to formulate varnishes.
Some Metals of the Last Century
Authors: Goodway Martha
Published: April 2011

The Twentieth Century can be looked back upon as a period in which a number of metal alloys unknown to previous centuries were introduced Some were alloys in unusual combinations of previously-used metals, but also elements little used earlier. Some of these alloys have already had their day and exist now only in museum collections, where they may also present problems of preservation. Many metals lost their traditional applications or added entirely new ones. Elements such as uranium and the semimetals that had been of interest only to the ceramist at the start of the century are now the bases of industries unforseen only a hundred years ago. From this it is concluded that predictions for the present century are uncertain.
Wrought Iron Wire from the Wheeling Suspension Bridge: a Metallurgical Assessment
Authors: Elban Wayne L. , Goodway Martha
Published: April 2011

The Wheeling Suspension Bridge was constructed in 1849 over the Ohio River as a part of the National Road connecting the east coast with the interior of the United States. This was just before introduction of the Bessemer process opened the Age of Steel, so the wire for the suspension cables was manufactured from wrought iron by a local Wheeling firm. The Bridge is still standing and carries both pedestrian and vehicular traffic. Samples of wire from the suspension cables were provided courtesy of Prof. Emory L. Kemp of West Virginia University, and were examined metallurgically by optical microscopy and with a scanning electron microscope for features such as inclusions, grain size, and morphology. Hardness was measured as a proxy for strength. The combined results are compared with earlier observations made of wire of finer gauge drawn for historical musical instruments.
Egyptian Faience Inlay Techniques: a process for obtaining detail and clarity by refiring
Authors: Riccardelli Carolyn , Mass Jennifer , Thornton Jonathan
Published: April 2011

The faience of the New Kingdom period is frequently decorated with an expanded palette of red, black, and yellow. This polychrome decoration was often accomplished by inlaying one color of paste into another. The aesthetic success of these inlay techniques reveals a fundamental understanding of the materials' characteristics before, during, and after firing, and knowledge of how to manipulate these characteristics. The goal of this research is to more fully understand ancient Egyptian faience inlay techniques by characterizing the properties of a set of standard reproductions. As the most aesthetically successful reproductions were obtained using pre-fired components, a series of experiments was performed to quantify changes in glaze color, glaze gloss, and depth of glaze penetration upon refiring. Data was gathered from replicated samples and cross-sections using SEM, UV-VIS spectrophotometry, colorimetry, and optical microscopy. Visual comparisons were made between cross-sections of replicated inlays and examples of broken ancient Egyptian faience inlays.
Core Vessel Technology: A New Model
Authors: Giberson Dudley F.
Published: April 2011

Ancient Egyptian XVIII Dynasty core vessel manufacturing technology had many sequential steps to make a core vessel, but there were only three essential elements to the process. One, the base layer of glass was applied as a fritted powder; two, the objects were manufactured over a vertical heat source; and three, the vessels were made in very low temperatures (maximum of about 800°
Hydration and Crystallization Pressure of Sodium Sulfate: a Critical Review
Authors: Flatt Robert J. , Scherer George W.
Published: April 2011

The two most frequently mentioned mechanisms used to explain the severe damage that occurs when a porous material, containing the anhydride phase of sodium sulfate, is exposed to either water or rising humidity are critically reviewed. Both derivations are presented along with their underlying hypotheses. Critical differences are discussed and it is concluded that crystallization pressure is the relevant mechanism. In effect however, it is shown that the expressions obtained both for crystallization pressure and hydration pressure are quite similar.
Hygric Swelling of Portland Brownstone
Authors: Gonzalez Inmaculada Jimenez , Higgins Megan , Scherer George W.
Published: April 2011

Portland Brownstone (PB) is a widely used building material, particularly in New York City, that is susceptible to severe deterioration from weathering. This stone contains clays that may cause damage by dilating during wetting/drying cycles. We have measured the swelling strain of PB in aqueous solutions to determine the effect of ionic strength (of KCl and CaCl2) and water activity (in isopropanol solutions). We have also measured the stress exerted during swelling when the expansion is constrained. These data permit calculation of the stresses produced during wetting/drying cycles, which are found to be comparable to the tensile strength of the stone.
Design and evaluation of restoration mortars for historic masonry using traditional materials and production techniques
Authors: Moropoulou Antonia , Bakolas Asterios , Moundoulas Petros , Aggelakopoulou Eleni , Anagnostopoulou Sofia
Published: April 2011

Cement based mortars used for historic masonry restoration presented unsatisfactory results, due to their chemical and physico-mechanical incompatibility to original buildings. In the present research, several syntheses of restoration mortars are produced using traditional techniques and materials such as binders (aerial and natural hydraulic lime), pozzolanicadditives (natural and artificial pozzolanas) and aggregates (sand and crushed brick). The technical characteristics of the mortars were determined using mechanical tests (compressive and flexural) and mercury intrusion porosimetry measurements at the time of 1, 3, 9, 15 months of curing. Water absorption measurements were performed at the time of 9 and 15 months curing, in order to evaluate mortars microstructural characteristics, their rate of water absorption and the total percentage of absorbed water. The aerial lime - artificial pozzolana mortar presented the best mechanical and microstructural performance. Hydraulic mortars acquired the maximum of the mechanical strength in 1 month, lime - pozzolana mortars in 3 months while aerial lime mortars continue to gain mechanical strength even in 15 months curing. Furthermore, the use of ceramic aggregates produces lightweight and elastic mortars, compatible to historicones.
Batch Material Processing and Glassmaking Technology of 9th Century B.C. Artifacts Excavated from the Site of Hasanlu, Northwest Iran
Authors: Stapleton Colleen P. , Swanson Samuel S.
Published: April 2011

The site of Hasanlu is located southwest of Lake Urmia (Lake Rezaiyeh) in the province of Western Azerbaijan, northwest Iran. Excavations carried out by Dr. R. H. Dyson, Jr. of the University of Pennsylvania from 1957 to 1977 of the Iron Age levels at Hasanlu yielded a large number of glass beads, as well as glass vessels, and glass furniture inlays or wall fittings. Sampling of many of these pieces was limited to weathered areas, requiring the use of a micro-analytical technique to characterize the glass. Electron microprobe and wavelength dispersive analysis were used to characterize the chemical compositions of the glasses of Hasanlu. The glasses are soda-lime-silica in composition, containing about 17-21 wt% soda and 2-8 wt% lime. of 51 glasses analyzed to date, 47 contain about 1-6 wt% of magnesia and 1-4 wt% potash, indicative of a plant ash source of alkali. Four glasses contain less than 1 wt% each of magnesia and potash, suggesting that these may have been made with a mineral alkali source like natron.

At least 35 glasses contain inclusions of partly reacted batch materials. In blue transparent to translucent, black translucent, and yellow opaque glasses, large, 0.2 mm diameter, droplets of alkali sulfates exhibit features that indicate they were an immiscible liquid coexisting with a surrounding silicate liquid. These sulfate droplets, which appear to be relatively common in the glasses found at Hasanlu, are probably the scum or “gall” that can form during melting of poorly prepared plant ash. Remnants of original raw colorants occur in a few glasses. Many of the black glasses contain polymetallic sulfides of different combinations of lead, copper, antimony, and iron. These inclusions and the glass chemistry are used to interpret the origin and processing of the batch materials, and the conditions under which the materials were melted.
Dressing Technology for the Silver Ore in “Iwami” Silver Mine Site, Japan
Authors: Murakami Ryu , Takada Jun , Torigoe Toshiyuki , Matsumoto Iwao , Toya Yoshio , Morioka Shouji , Oguni Haruo , Endou Hiromi , Nakada Ken-ichi
Published: April 2011

In the early modern age Japan was a kingdom rich in metal resources. A lot of gold, silver and copper were produced and exported to foreign countries, nevertheless Japan maintained a national isolation policy. The Iwami silver mine located in Shimane prefecture was the representative silver mine that prospered most. It produced about 10 % of the world's silver output. It is now mostly abandoned and reduced to ruins. Only a famous picture scroll remains to indicate its real activities. Through archaeological excavation started in 1983, it is becoming clear that extensive remains of mining and smelting are preserved. From 1996 scientific investigation of the excavated remains has been conducted. During excavation, and confirmed by scientific research, we recognized that the artifacts deposited during both the mining of the silver ore and the smelting process could be classified into two artifactual types; objects and fragments produced in the dressing process that were not influenced by a heating process and objects influenced by a heating process and produced by smelting and refining. The low grade ore, waste and tailings (remains after gravity concentration) that were scrapped in the dressing process are included in the former type, and the furnace fragments for smelting and refining, tuyeres (blast pipes) and slag and other smelter remains are of the latter type. The waste and tailings scrapped in the dressing process have not previously been studied. This study aimed at systematically investigating the dressing technology and estimating the ore grade through the evaluation of the range of variation in the waste and tailings left as scrap in the dressing process. The analytical results revealed the actual activities practiced at the Iwami silver mine in the dressing process.
Study on the Green Glaze from Qionglai Kiln Site in Sichuan: One of the Earliest Phase-Separated Opaque Glazes in China
Authors: Li Weidong , Wu Jun , Li Jiazhi , Guo Jingkun
Published: April 2011

The Qionglai kiln site is a famous folk kiln site in Sichuan province, China, of the Tang dynasty (618-907 A.D.). The wares from Qionglai kiln site bear a unique national style and striking local features. A series of opaque green-glazed shards with mild gloss and jade-like feel, excavated from Shifangtang kiln site were selected as test samples. The glaze and body compositions and microstructures of the shards were studied by means of EDXRF, FESEM and DTEM/SAD/EDS. The study has demonstrated that the opaque green glazes from Qionglai kiln site are high-temperature calcia-magnesia-silicate glazes and that typical phase-separated glazes of the droplet structure. The isolated droplets are rich in SiO2 and the matrix is rich in oxides of Ca, Mg, P, Ti and Fe. We have shown that Al2O3 suppresses phase separation. The droplet diameter falls in the range of 0.1-0.4 –m, causing intensive light scattering, and resulting in good opacification and jade-like texture. The green Glaze from Qionglai Kiln Site is one of the earliest phase-separated opaque glazes in China. The study also shows that there is a close relationship of compositions between Qionglai kiln and Changsha kiln.
Experimental investigation of silvering in late Roman coinage
Authors: Vlachou C. , McDonnell J.G. , Janaway R.C.
Published: April 2011

Roman Coinage suffered from severe debasement during the 3rdcentury AD. By 250 AD., the production of complex copper alloy (Cu-Sn-Pb-Ag) coins with a silvered surface, became common practice. The same method continued to be applied during the 4thcentury AD for the production of a new denomination introduced by Diocletian in 293/4 AD. Previous analyses of these coins did not solve key technological issues and in particular, the silvering process. The British Museum kindly allowed further research at Bradford to examine coins from Cope's Archive in more detail, utilizing XRF, SEM-EDS metallography, LA-ICP-MS and EPMA. Metallographic and SEM examination of 128 coins, revealed that the silver layer was very difficult to trace because its thickness was a few microns and in some cases it was present under the corrosion layer. Results derived from the LA-ICP-MS and EPMA analyses have demonstrated, for the first time, the presence of Hg in the surface layers of these coins. A review of ancient sources and historic literature indicated possible methods which might have been used for the production of the plating. A programme of plating experiments was undertaken to examine a number of variables in the process, such as amalgam preparation, and heating cycles. Results from the experimental work are presented.
A New X-Ray Scattering Method for Determining Pore-Size Distribution in Low-k Thin Films
Authors: Omote Kazuhiko , Kawamura Shigeru
Published: April 2011

We have successively developed a new x-ray scattering technique for a non-destructive determination of pore-size distributions in porous low-κ thin films formed on thick substrates. The pore size distribution in a film is derived from x-ray diffuse scattering data, which are measured using offset θ/2θ scans to avoid strong specular reflections from the film surface and its substrate. Γ-distribution mode for the pores in the film is used in the calculation. The average diameter and the dispersion parameter of the Γ-distribution function are varied and refined by computer so that the calculated scattering pattern best matches to the experimental pattern. The technique has been used to analyze porous methyl silsesquioxane (MSQ) films. The pore size distributions determined by the x-ray scattering technique agree with that of the commonly used gas adsorption technique. The x-ray technique has been also used successfully determine small pores less than one nanometer in diameter, which is well below the lowest limit of the gas adsorption technique.
Properties of Sputtered Bilayer WNx/W Diffusion Barriers between Si and Cu
Authors: Leedy K. D. , O'Keefe M. J. , Dahlgren E. J. , Grant J. T.
Published: April 2011

Copper interconnect metallizations in next generation integrated circuits will require thin diffusion barrier layers (<20 nm) between the Cu and low-k dielectric which may also function as seed layers for subsequent material depositions. One possible structure entails a multicomponent diffusion barrier with a lower resistivity component, such as W on WNx. In this study, sputtered WNx/W bilayer thin films were investigated as diffusion barriers between Si and Cu. The total thickness of the WNx/W bilayer was fixed at 20 nm while the WNx thickness was varied from 0 to 20 nm. After deposition of the barrier films, a 100 nm thick Cu film was sputtered over the top of the á-W and amorphous WNx bilayer. The as-deposited WNx/W film stress was found to be strongly dependent on the relative amount of WNx and W present and the addition of a Cu overlayer was found to mitigate the stress levels. The WNx/W barriers remained stable after 650°C anneals and exhibited phase transformations to W2N. Microstructural characterization using transmission electron microscopy and x-ray diffraction and chemical analysis by x-ray photoelectron spectroscopy of the films were used to identify the as-deposited and transformed phases.
Understanding the Morphologies and Polymerization Mechanism of Homopolymer and Block Copolymer Brushes by Living Anionic Surface Initiated Polymerization
Authors: Park Mi-Kyoung , Sakellariou George , Pispas Stergios , Hadjichristides Nikos , Mays Jimmy , Advincula Rigoberto
Published: April 2011

Homopolymer and block copolymer brushes grafted from Au and Si (SiOx) surfaces via living anionic surface initiated polymerization (LASIP) has been reported. 1,1-diphenylethylene (DPE) derivative, an initiator for anionic polymerization, was grafted onto planar Si-wafer and Au surfaces by self-assembled monolayer (SAM) techniques. n-BuLi was used to activate the DPE for anionic polymerization of monomers at the interface under high vacuum. By a careful sequence of monomer introduction, reaction, and termination, homopolymer and block copolymer tethered polymer brushes were obtained. The importance of initiator activation, control of polymerization conditions, and removal of excess BuLi is emphasized. Interesting differences in morphology, thickness, grafting density, and polymerization conditions contrasts LASIP from solution and other surface initiated polymerization (SIP) mechanisms. The formation of block copolymer sequences highlights the unique utility of a living anionic polymerization technique on surfaces.
Single Shot of Arf Laser-Induced Photochemical Nucleation of Copper on Polyethylene-Terephthalate Surface
Authors: Tokunaga H. , Murahara M.
Published: April 2011

Copper nuclei was grown on a PET surface in the copper sulfate water solution ambience with only one shot of ArF laser.· General electronic circuit printed boards have been made by sticking the copper foils with adhesive agents after having made the foil surface rough. Consequently, even the printed board of low conductivity might generate a high frequency noise due to the difference between the copper foils and adhesive agents. If atoms composing plastics and metal could be combined by a chemical method instead of the conventional physical methods, a hybrid material made of both plastics and metal would be produced.

We have reported for the substitution of copper atoms on an all-aromatic-polyimide surface by a single shot of ArF laser irradiation In this study, with one single shot of ArF laser, we succeeded in growing the Cu nuclei on the PET film whose ultraviolet absorption is lower than all-aromatic-polyimide. The sample surface was photo-oxidized with the Xe2 excimer lamp in pre-treatment. A fused silica glass was placed on the sample surface, and the sulfate water solution was poured into the gap between the glass and the sample to form a thin liquid layer. Then, the sample was vertically irradiated once by the circuit patterned ArF laser light with the laser fluence of 28mJ/cm2. The photo-dissociated copper atom formed the C-O-Cu bond with active oxygen to sub stitute on the PET surface. The modified sample was, then, immersed in the electro less plating solution at 60 degrees Celsius for 15 minutes; the copper thin film of about 24mm was grown on the modified surface.