bluuebunny/crossref_metadata_2025 huggingface dataset:
Orientation of Ferroelectric Liquid Crystals by Self-Assembled Bilayer Molecular Assembly
Authors: Jain Sukhmal C. , Dixit Vivechana , Tanwar Vinod K. , Shivaprasad S. M.
Published: April 2011

Molecular films of amino propyl triethoxy silane (APTES) attached with cinnamoyl moieties were deposited on indium tin oxide (ITO) coated glass and quartz substrates by self-assembly technique. The deposition of the monolayer films resulted in a large change in the wettability of the substrates. X-ray photoelectron spectroscopy (XPS) and UV-spectroscopy were used to study the structure and properties of the grown films. The molecular assembly was photodimerized by irradiating it with a linearly polarized UV-light. Thus created polymer-solid interface has been shown to produce good, stable planar orientation of ferroelectric liquid crystal mixtures. The electro-optical and switching properties of the ferroelectric liquid crystal cells have been investigated and found to be quite similar to those prepared in conventional manner.
Light-Controllable Chiral Photochromic Multifunctional Liquid Crystal Polymers
Authors: Shibaev Valery P. , Bobrovsky Alexey Yu. , Boiko Natalia I.
Published: April 2011

A new family of light-controllable chiral photochromic multifunctional liquid crystalline (LC) side-chain acrylic polymers consisting of nematogenic, chiral and photochromic monomer units was obtained. The new principle of photoregulation of the helical supramolecular structure and optical properties of the binary and ternary chiral photochromic LC polymers based on the change of helical twisting power of the chiral photochromic monomer units was developed. The features of photooptical behaviour of LC polymers possessing the dual photochromism and the peculiarities of optical data recording based on the photochemical spectral gap burning were presented and discussed. The synthesized polymers are shown to be promising candidates for colour data recording and storage.
A Molecular Dynamics Simulation Study of the Nonlinear Optical Response of Liquid Crystalline Systems
Authors: Kiyohara Kenji , Ohta Koji , Shimizu Yo
Published: April 2011

We investigated the third-order nonlinear optical response of a Gay-Berne system at the isotropic, nematic, and smectic phases by molecular dynamics simulation. The components of the optical response were calculated for the three different axes with respect to the director of the system, separately. In the nematic phase, in particular, we observed that the response function does not vanish at long times. This means that the orientation of the director of the system is permanently changed by an instant irradiation of polarized light, as a result of third-order nonlinear optical response. In the smectic phase, however, all the components of the response function decay quickly. Our results give a theoretical background at molecular level on the interpretation of the reported experimental observations of peculiar dynamics of liquid crystalline systems at irradiation of laser lights.
Investigation of Polymer Stabilized Liquid Crystal Formation Using Fluorinated and Aliphatic Monoacrylates
Authors: McCormick Demetrius , Guymon C. Allan
Published: April 2011

This study focuses on the photo-polymerization of a fluorinated monoacrylate monomer and aliphatic analog within a room temperature smectic liquid crystal (LC) in an effort to understand how factors such as LC order, monomer segregation, and monomer chemical structure affects the polymerization mechanism in polymer stabilized liquid crystalline systems (PSLC). Specifically, a fluorinated monoacrylate exhibits significantly enhanced polymerization rates when compared to an aliphatic monoacrylate. Moreover, this rate enhancement is particularly pronounced in the smectic phase of the LC, where the fluorinated monoacrylate displays a polymerization rate in the smectic phase that is over three times faster than the aliphatic monoacrylate in the smectic phase. Also the fluorinated monoacrylate exhibits enhanced segregation between the smectic layers of the LC both before and after polymerization, whereas the aliphatic monoacrylate phase separates during polymerization. The results of this study demonstrate how changes in the monomer chemical structure (i.e. fluorination) can significantly impact the polymerization mechanism and segregation in polymer stabilized systems. This study also offers the potential to further the understanding of tailoring these unique systems for display applications.
Structure properties Relationships of Dendritic and Multipodal Liquid Crystal Materials based on Carbosilazane Cores
Authors: Elsäßer R. , Martin D. Rodriguez , Richardson R. M. , Photinos D. J. , Goodby J. W. , Veith M. , Mehl G. H.
Published: April 2011

The synthesis of the first inorganic-organic hybrid liquid crystal dendrimers based on carbosilazane cores, which exhibit enantiotropic nematic and smectic C and columnar phase behaviour is presented and the liquid-crystalline phase properties and the phase structures are discussed.
Semifluorinated Polymeric Liquid Crystals as A Mechanistic Tool to Study The Effects of Interfacial Energies on The Orientation of Liquid Crystals
Authors: Perahia Dvora , Traiphol Rakchart , Smith Dennis W.
Published: April 2011

Obtaining spontaneous orientation and fast collective response of ultra thin liquid crystalline (LC) layers to external stimuli without memory effects, is one of the major challenges in achieving the next generation of LC devices. The relationship between interfacial energies, structure and dynamics of support layers and their effects on surface orientation of liquid crystals has been investigated. A model polymeric system, containing a mesognic group, α- methylstilbene as anchoring group, bridged by an energy controlling moiety, fluorocyclobutyl, has been used to obtain substrates with controlled surface energy and structure. Neutron reflectivity was used to study the surface structure of the polymer. The orientation of a well characterized liquid crystal, 8CB that exhibits both nematic and Smectic phases, was studied by optical microscopy and small angle X-ray scattering. Correlation between the surface structure of the polymeric layer and the orientation of the Smectic phase indicated direct correlation between the surface orientation and the concentration of fluorine at the interface.
Characterization of Thin Polymer Blend Films using ESEM – No Charging, No Staining.
Authors: Bache Ian C. , Ramsdale Catherine M. , Thomas D. Steve , Arias Ana-Claudia , MacKenzie J. Devin , Friend Richard H. , Greenham Neil C. , Donald Athene M.
Published: April 2011

Characterising the morphology of thin films for use in device applications requires the ability to study both the structure within the plane of the film, and also through its thickness. Environmental scanning electron microscopy has proved to be a fruitful technique for the study of such films both because contrast can be seen within the film without the need for staining (as is conventionally done for electron microscopy), and because cross-sectional images can be obtained without charging artefacts. The application of ESEM to a particular blend of relevance to photovoltaics is described.
The Use of Aqueous Enzymatic Polymerization of Amphyphilic Alkyl Tyrosine Derivatives as Environmentally Benign Coatings in the Microelectronics Industry
Authors: Angelopoulos Anastasios P. , Marx Kenneth A. , Oh Kyoung S.
Published: April 2011

The surface coating properties of enzymatically polymerized decyl esters of d-tyrosine from aqueous solutions onto gold surfaces have been investigated utilizing the complementary techniques of Potentiometeric Titration, UV-VIS Spectroscopy, and X-ray Photoelectron Spectroscopy (XPS). The aqueous-based coatings are of interest as environmentally friendly and cost-effective replacements for epoxy-based coatings currently employed in the microelectronics industry for both chemical protection and electrical insulation of gold-covered metallic conductors. Experimental results with respect to polymerization pH, immersion pH, and immersion time are presented and compared to the ionization behavior of the monomers in solution. Optimum processing conditions have been established, which yield uniform aqueous-based polymeric coatings on gold conductor surfaces.
Secondary Ion Mass Spectroscopy Study of Failure Mechanism in Organic Light Emitting Devices
Authors: Ke Lin , Zhang Keran , Kumar Ramadas Senthil , Chua Soo Jin , Yakovlev Nikolai
Published: April 2011

Secondary ion mass spectroscopy is used to examine the dark, non-emissive defects on the organic light-emitting device. Boundary movements are originated from electrode imperfection. Due to flexibility and movability of polymer layer, distribution variations and a more severe Indium and Calcium overlapping are detected in dark spot defect area. Boundary movements are not in good agreement between different layers. Interfaces became undulate. The closeness and proximity between the In sharp spikes and cathode metal protrusion leads to the initial point of dark spot. We demonstrate that the presence of cathode imperfection and interface roughness of different layers correlated to the device dark spot formation.
Molecular Dynamics Studies on the Effects of Water Speciation on Interfacial Structure and Dynamics in Silica-Filled PDMS Composites
Authors: Gee Richard H. , Maxwell Robert S. , Dinh Long N. , Balazs Bryan
Published: April 2011

Significant changes in materials properties of siloxane based polymers can be obtained by the addition of inorganic fillers. In silica-filled polydimethylsiloxane (PDMS) based composites the mechanism of this reinforcing behavior is presumably hydrogen bonding between surface hydroxyls and backbone siloxane species. We have chosen to investigate in detail the effect of chemisorbed (hydroxyls) and physisorbed water on the interfacial structure and dynamics in silica-filled PDMS based composites. Toward this end, we have combined molecular dynamics simulations and experimental studies employing DMA and NMR analysis. Our results suggest that the polymer-silica contact distance and the mobility of interfacial polymer chains significantly decreased as the hydration (hydroxyl and/or physisorbed water) level at the interface was reduced. The reduced mobility of the PDMS chains in the interfacial domain reduced the overall motional properties of the polymer, thus causing an effective "stiffening" of the polymer matrix. The role of the long-ranged Coulombic interactions on the structural features and chain dynamics of the polymer were also examined. Both are found to be strongly influenced by the electrostatic interactions as identified by the bond orientation time correlation function and local density distribution functions. These results have important implications for the design of nanocomposite silica-siloxane materials.
Comparison of Mobility Modes in Polymer Solutions Undergoing Thermal-Induced Phase Separation
Authors: Chan Philip K.
Published: April 2011

The thermal-induced phase separation method is used to fabricate polymer membranes and polymer-dispersed liquid crystal films from polymer solutions. The resultant morphology consists of solvent droplets dispersed uniformly in a solid polymer matrix. Up till now, the modeling and computer simulation of the thermal-induced phase separation phenomenon in polymer solutions have considered the mobility to be a constant. The objective of this presentation is to compare the following three mobility modes: (1) mobility as a constant, (2) mobility following fast mode theory, and (3) mobility following slow mode theory. We present computer simulation results from models composed of the Cahn-Hilliard theory for phase separation, Flory-Huggins free energy density for polymer solutions, and the three aforementioned mobility modes. The numerical results indicate that there is no significant difference in the morphology formed; the only difference occurs in the phase separation time. Furthermore, the numerical results show that the only difference between the slow and fast mode theories is a factor of two; the mobility of the fast mode theory is twice that of the slow mode theory.
The Effect of Carbon Black and Colloidal Silica Fillers on the Fracture Toughness at Polymethylmethacrylate Interfaces
Authors: Bronner Mordechai J. , Shah Anshul A. , Kim Hyun-Joong , Peiffer Dennis G. , Rafailovich Miriam , Sokolov Jonathan
Published: April 2011

We have measured the fracture toughness of PMMA slabs with carbon black and colloidal silica fillers placed at the interface. The results show that the fracture toughness decreases linearly with carbon black concentration. The fracture toughness scales as annealing time, t1/2indicating that it is diffusion limited. Addition of Colloidal Silica drastically reduces the fracture toughness regardless of concentration and annealing time. These results indicate that carbon black introduces physical cross links which decrease dynamics whereas colloidal silica produces permanent chemical cross links which prevent diffusion across the interface.
Surface Characterization of DNA Microarray on Silicon Dioxide and Compatible Silicon Materials in the Immobilization Process
Authors: Xu Wen , Li Jiong , Xue Mei , Carles Maria , Trau Dieter Wilhelm , Lenigk Ralf , Sucher Nikolaus J. , Ip Nancy Y. , Chan Mansun
Published: April 2011

In this work, the surface properties of a DNA microarray formed on silicon based solid support are studied at different stages during the hybridization process. A modified immobilization process using the covalent immobilization of thiol-terminated DNA oligonucleotides on self-assembled layers of (3-mercaptopropyl) trimethoxysilane (MPTS) by disulfide bond formation is used to selectively attach DNA probes onto the surface of silicon dioxide. Contact angle measurement is used to monitor the bonding of MPTS on the surface. Atomic force microscopy (AFM) shows an increase in particle size before and after the growth of the MPTS layer. Fluorescence microscopy reveals the success of hybridization of complementary oligonucleotides labeled by FAM to the probe. The effects of modified immobilization process on other common material in silicon processing are also studied. As a result of the corrosive chemical used in the process, common metals used in micro-fabrication processes like aluminum are etched away. Silicon nitride is not affected by the immobilization and hybridization process, and thus can be used as a passivation and isolation material to conform the DNA to a specific area for DNA microarray to reduce cross-talk. The fluorescence image from the scanner indicates silicon nitride can effectively be used as an isolation material with linewidth down to 1 μm.
Calcium Phosphate Coating on Titanium Plates by Electrodeposition
Authors: Ishikawa Masahiko , Nishikawa Kouji , Kuroda Kensuke , Ryoichi Ichino , Okido Masazumi , Takai Osamu
Published: April 2011

Calcium phosphate films were deposited on titanium electrodes cathodically from CaCl2·2H2O and Ca(H2PO4)2 · H2O aqueous solutions. In this study, H2O2 addition into electrolytes was applied to enhance the electrochemical process at the solution/electrode at a smaller cathodic potential than no H2O2 addition. Deposited films were analyzed by scanning electron microscopy (SEM) observation and X-ray diffraction (XRD). Cathodic current of the Ti electrode decreased once and increased in the solution with H2O2. It shows a cathodic current peak at c.a. 25 min in the case of potentiostatic condition at - 0.756 V (vs. Ag - AgCl, sat. KCl). The calcium phosphate film grows mainly with the decrease in current after the cathodic peak. The characteristics for the electrodeposited film such as crystal morphology depends on cathodic potential, solution pH, deposition temperature and amount of H2O2 addition. Dense calcium phosphate film composed of relatively good crystalline was obtained at pH 5.5 and – 0.756 V. Film adhesion on Ti appeared to be strong by peeling test. At larger cathodic potential of – 1.156 V, the film coverage on titanium plates was smaller and film adhesion worsened. Larger cathodic polarization of more than – 1.556 V was necessary to reduce water in case without H2O2 addition.
Processing, Magnetization and Structural Studies of Bioactive Ferromagnetic Glass-Ceramics
Authors: Leventouri Theodora , Kis Antonella C. , Sorge Korey , Bunaciu Camelia E. , Thompson James R.
Published: April 2011

A series of ferromagnetic bioceramic samples in the system 45(CaO, P2O5), ySiO2xFe2O3 were synthesized with various processing parameters in order to study correlations between structure, magnetic properties and preparation variables. X-ray powder diffraction shows that the qualitative as well as the quantitative structure of the samples is strongly affected by processing parameters, including composition, annealing temperature and the chemical reactions. Magnetic measurements illustrate a strong correlation between the saturation magnetization, and hysteresis loss, with the processing parameters of the material.
Development of No-Rejection Aqueous Humor Pressure Control Membrane in The Eyeball for Glaucoma Implant Devices
Authors: Sato Y. , Parel J.M. , Murahara M.
Published: April 2011

The inner porous part of the PTFE [poly-tetrafluoroethylene] membrane was substituted with a hydrophilic group using irradiation by an ArF laser. Water was employed for a defluorination agent in order to inhibit rejection. The membrane was developed that automatically pumps out water when the pressure is raised above a fixed value. The increased intraocular pressure with aqueous outflow failure causes glaucoma. In healthy humans intraocular pressure is maintained at a normal physiological level of between 8 to 18 mmHg. When the pressure exceeds 21 mmHg, a diagnostic of glaucoma may be predicted.

We designed a new type of membrane to pump the aqueous humor and regulate its outflow. The membrane has gained characteristics of aqueous humor penetration by substituting a part of a hydrophobic group that exists inside the porous PTFE with the hydrophilic group. Furthermore our previous studies have found that B, Al and H atoms are effective for defluorination of atoms from fluorocarbon. In this study three kinds of reaction liquid containing B, Al and H respectively were used. By this defluorination reaction B and Al atoms were better than H atoms. We prepared a boric acid water solution (B(OH)3), nitro aluminate water solution (Al(NO3)3) and water (H2O) as chemical compounds for defluorination and OH substitution. When ethyl alcohol is dropped on the porous PTFE, it penetrates into inner porous PTFE easily. When the three kinds of chemical compound water solutions are dropped onto the porous PTFE membrane, the solution is trapped up to the inner side of porous PTFE. When each sample with hydrophilic property treatment was implanted into rabbits' eyes and its biocompatibility was tested, some samples using Al and B atoms for defluorination have shown the rejection reaction called neoplasm blood vessel. However, the other samples using water as the reaction liquid have shown no rejection.
Non-destructive analysis of Nineteenth century Scottish calotype negatives and salt prints
Authors: Eremin Katherine , Tate James , Morrison-Low Alison , Berry James , Stevenson Sara
Published: April 2011

Nineteenth century negatives and positives in the collections of the National Museums of Scotland (NMS) and the National Galleries of Scotland (NGS) were analysed non-destructively to identify the techniques used in their manufacture. Modern positive and negative images prepared using known nineteenth century processes were also analysed for comparison. Air-path energy dispersive x-ray fluorescence analysis and controlled pressure scanning electron microscopy with energy dispersive microanalysis enabled the images to be divided into groups based on the levels of bromine, iodine and silver, and the likely processes used inferred. An early group of positives were probably sensitised with either silver chloride or silver bromide and fixed with potassium bromide. However, most positives were probably sensitised with silver chloride and fixed with sodium thiosulphate. Most negatives were probably sensitized with silver iodide and fixed with potassium bromide (predominant), sodium thiosulphate or potassium iodide. Cobalt and arsenic are present due to the use of smalt in the production of white paper. Copper and zinc are attributed to incorporation of fragments of brass buttons left on the rags used in paper production, observed as small blue spots. The presence of iron, sometimes visible as orange spots, may be from rust off the paper making machines.
Recovering and Re-Discovering Craft
Authors: Vandiver Pamela B.
Published: April 2011

Many studies have shown that craft involves know-how, practice and problem solving that represents activities that can be recovered by study of various artifact assemblages and contexts within archaeological sites. The types of conclusions differ with nature of the research question, sample size and its variability, methods of study and organization of collecting in the field, as well as the results of areal study: ethnographic information, resource survey and landscape reconstruction. Questions generated through analysis of materials, processes and properties often generate questions that can only be answered by replicative experiments of all aspects of a chaine operatoire, only part of it or only those critical aspects about which questions remain. The integration of the laboratory/workshop results with the archaeological evidence, both objects and context, can lead to a re-discovery of craft. The conjectured details of materials composition and structure, sequence of processing, properties, performance or use essentially reverse engineer the typical way that modern materials research is conducted. This paper aims at developing a widening dialogue about craft know-how among materials scientists working in museums and artist-craftsmen. To learn about our history and the human condition is not just to analyze and preserve the objects and artifacts, but also to investigate and understand the knowledge and skills used to produce and use them-- essentially this is the preservation of intangible cultural heritage and culture history.
The Characterization and Conservation of Aged Aluminum Alloys: Buckminster Fuller's Dymaxion House
Authors: Trentelman Karen A. , Ashby James , Donlon William T.
Published: April 2011

The Dymaxion House is a unique historic dwelling structure designed by Buckminster Fuller. Built in the 1940s, the house was constructed of modern materials, most notably aluminum, which formed the walls, roof and many of the structural elements. The challenge faced in reconstructing the Dymaxion House at Henry Ford Museum & Greenfield Village was to preserve the original structure as much as possible while simultaneously accommodating the needs of exhibition (i.e. to restore the visual appearance and ensure sufficient structural integrity to allow the entrance of visitors). The primary aluminum alloys used in the house are equivalent to the modern alloy designations 2014 and 2024; both extruded forms and Alclad sheets were used. The alloy composition, age-hardening characteristics, cladding layers, grain structure and corrosion products of the aged aluminum components of the Dymaxion House have been studied. The results of these studies were used in consultation with conservators, engineers and corrosion scientists to determine the most appropriate course of treatment.
Assessment of Cleaning Conservation Interventions on Architectural Surfaces Using an Integrated Methodology
Authors: Moropoulou Antonia , Delegou Ekaterini T. , Avdelidis Nicolas P. , Koui Maria
Published: April 2011

In this work, pilot cleaning interventions applied by a wet micro-blasting method on architectural surfaces of three historic buildings in marble and porous stone were evaluated in situ and in the laboratory. The investigation was performed on characteristic stone surfaces (marbles and porous stone) of the following historic buildings: Athens Academy and National Library of Greece in Athens center polluted urban environment and Bank of Greece in Piraeus marine environment. The materials of the facades were characterized, and the mechanism of decay was diagnosed. In addition, the cleaning method's efficiency was evaluated based on the acceptability of the alteration of the cleaned architectural surfaces. Criteria were both aesthetic and physico-chemical. In particular, the architectural surfaces were examined in situ by the means of fiber optic microscopy, infrared thermography and colorimetry. In the laboratory, methods of investigation were optical microscopy, X-ray diffraction, scanning electron microscopy with energy dispersion by X-ray analysis, mercury intrusion porosimetry, Fourier transform infrared spectroscopy, conductivity and pH measurements. The majority of measurements and analyses were applied before and after the pilot cleaning interventions. Finally, the results of this study contribute to the development of an integrated methodology for the assessment of cleaning interventions applied on architectural surfaces.
Rheology Optimization of Particle Modified Consolidants
Authors: Aggelakopoulou Eleni , Charles Pamela , Acerra Matilde E. , Garcia Ana I. , Flatt Robert J. , Scherer George W.
Published: April 2011

Ethyl silicate-based consolidants are used to restore strength to degraded stones. One of the limitations of strength development using these products is their reported cracking behavior during drying. Particle Modified Consolidants (PMC) consist of a silicate matrix plus colloidal oxide particles. The presence of particles physically limits the silicate network from shrinking under capillary pressures, and thereby reduces strength loss during drying. In addition, the network maintains a higher permeability, because the dried consolidants remains porous. When the particles used are pigments, it is also conceivable to adjust the consolidant color. Moreover, a careful choice of particles should allow matching the thermal dilatation of the consolidant to that of the stone. An important limitation to further development of PMC has been the ability to avoid particle agglomeration in the dispersion. When agglomerates are present, not only do they increase the viscosity but they also can block pore entrances, preventing consolidant fromentering the stone. In this work we demonstrate the feasibility of adsorbing nano-silica particlesonto pigment particles to create a steric barrier to agglomeration. Rheology and density measurements confirm that the resulting dispersion is fluid and stable against settling. The consolidant readily penetrates Ohio Massilian sandstone, providing improved strength, stiffness, and salt resistance, compared to a commercial silicate consolidant.
Reconstructing the Materials and Technology of Egyptian Faience and Frit
Authors: Griffin Patricia S.
Published: April 2011

This paper presents a research project undertaken at the Cleveland Museum of Art to study and characterize its collection of more than one hundred and fifty Egyptian artifacts made from faience or frit. An overview of the project is presented here, followed by a summary of faience technology that draws upon other published studies as well as the insights gained during this project. Where appropriate, this technological discussion will be illustrated using examples of Egyptian artifacts studied during this project. For some objects discussion will be limited to one or two aspects of manufacture. However, the proposed manufacturing sequence of several key artifacts will be described more fully.

A multi-faceted approach to the study of these materials was designed. Examination procedures used to study the collection included microscopy (surface examination using a lowpowered microscope, and microstructural characterization of exposed fracture surfaces or small samples using a scanning electron microscope), structural analysis using Xero-radiography, and nondestructive qualitative compositional analysis of glazes and pastes using x-ray fluorescence spectroscopy. Hardness testing using fine metal points graded to the Moh's scale, Munsell color evaluations and qualitative gloss determinations were also employed. Replication experiments were used extensively to understand visual features remaining on the surfaces of objects, to provide comparison standards for examination of fracture surfaces with magnification, and to test the validity of theories on paste recipes and forming practices.

The primary goal of the project was to provide accurate descriptions of the materials and technology of each object as possible. This included characterization of technological features such as glaze (probable application method, composition, color, and gloss), paste (grain size, color, hardness, composition, and extent of vitrification) and forming methods (modeling, molding, template, cores, wet working and/or dry working). Careful documentation of these features enabled detailed technological descriptions to be prepared for each artifact. This work also elucidated many aspects of faience production as it may have been practiced in ancient Egypt, and suggested directions for further study. It is hoped that in the future, technological criteria for dating artifacts that cannot be securely dated using traditional typological art historical criteria can be developed by the careful documentation of characteristics of the paste, glaze and forming processes.
Analyzing Style and Technology in the Eastern Woodlands
Authors: Rieth Christina B.
Published: April 2011

Trace element analysis was used to assess the provenance of manufacture of ceramic vessels recovered from six Early Late Prehistoric sites (A.D. 700-1300) in the Susquehanna Valley of New York and Pennsylvania. The compositional profiles of 93 sherds were recorded and compared with the profiles of known clays in the valley. The results of this project suggest that the vessels from these sites form five different clay groups with most vessels manufactured from local clays. Some non-locally manufactured pots were also identified and may represent interaction between neighboring groups.
An Unusual Dark Patina on Egyptian Copper Alloy Objects in the Royal Ontario Museum Collection
Authors: Whyte Alison , Stock Susan , Murray Alison
Published: April 2011

The unusual appearance of a dark patina on a select group of Egyptian copper alloy objects in the Royal Ontario Museum (ROM) collection has raised the question of both its composition and formation and therefore, its authenticity. The purpose of this project was to determine both the constitution of the patina and the process by which it was formed. A cross section sample from one artifact was analysed using optical, metallurgical and scanning electron microscopy in order to clarify the relationship between the patina layer and the body metal. In addition, energy dispersive spectroscopy was employed to establish the chemical composition of the body metal. Surface samples were removed from all the objects and subjected to x-ray diffraction in order to identify the crystalline compounds present. Fourier transform infra-red spectroscopy was used to establish the presence of any organic compounds in the surface samples. Although further analysis is required, the results of the research suggest that the patina may have been formed as a result of a modern cleaning treatment possibly followed by an artificial re-patination treatment.
An Examination of Deterioration Products Found on Tin Ingots Excavated from the 14thCentury B.C., Late Bronze Age Shipwreck, The Ulu Burun, Near Kas, Turkey
Authors: Lipcsei Laura , Murray Alison , Smith Reginald , Savas Mahmut
Published: April 2011

The purpose of this study was to investigate the deterioration of tin ingots recovered from a late 14th century B.C. (Late Bronze Age) shipwreck off Ulu Burun (Kas) Turkey. As so little elemental tin has been excavated from underwater sites and preserved to date, the Ulu Burun ingots offer a unique opportunity to study the degradation products of ancient tin artifacts from a natural marine environment. The current investigation had three major objectives: to identify corrosion products; to confirm or refute the presence of ‘tin pest’, which has been asserted as one of the major reasons for the disintegration of the ingots and a topic of much controversy in the conservation and museum communities; and, finally, to contribute to the overall understanding of marine tin. The following instrumental techniques were used to analyze ingot samples: x-ray diffraction, atomic absorption, inductively coupled plasma emission spectroscopy. The results of the analysis have identified corrosion products that are characteristic of the type of products anticipated on tin objects from a marine environment. The presence of the controversial tin pest disease was confirmed in two of the six samples tested. Sample preparation appears to be a potential factor in the determination of tin pest using XRD.
Reproduction of Japanese Traditional Pigment Based on Iron Oxide Powders With Yellowish Red Color
Authors: Asaoka Hiroshi , Nakanishi Makoto , Fujii Tatsuo , Takada Jun , Kusano Yoshihiro , Murakami Ryu
Published: April 2011

Since the beginning of the 18th century A.D., an artificial iron oxide pigment (hematite, called “bengara” in Japanese) and having a beautiful yellowish red color, has been produced in Japan and applied to pottery, textiles and paintings. However, in 1965 the traditional “bengara” could not be produced anymore, mainly because of environmental pollution. The purpose of this study is to make clear the features of traditional “bengara” and to reproduce high quality “bengara” using modern high-purity reagents. Traditional “bengara” has been characterized as hematite containing a small amount of Al. The average size of the “bengara” particles is approximately 100 nm. The color becomes more yellowish-red with increasing Al content. A monophase of hematite prepared by heating a mixture FeSO4-7H2O and α-Al2O3 to about 680 °C included a small amount of Al substituted in a solid solution. The particle size greatly decreased as the heat treatment temperature was decreased: 100 nm at 770 °C but 50 nm at 650 °C. The color of the particles becomes more vivid as the temperature is decreased, but within bounds this color is independent of the amount of Al in solid solution.
Lustrous Black Fine Ware at Gordion, Turkey: A Distinctive Sintered Slip Technology
Authors: Henrickson Robert C , Vandiver Pamela B. , Blackman M. James
Published: April 2011

Potters at ancient Gordion (Turkey) produced a distinctive fine ware with a black glossy finish during at least the period 700-500 BC. Visual examination suggested a sintered slip finish. Study using SEM, EDS, INAA, x-ray diffraction, and refiring has confirmed this hypothesis. The technology was characterized by a relatively low firing temperature, large amounts of flux, a darkening wash added over the slip, and use of both calcareous and non-calcareous clays.
Engineered Low Resistivity Titanium-Tantalum Nitride Films by Atomic Layer Deposition
Authors: Londergan Ana R. , Winkler Jereld L. , Vu Kim , Matthysse Lawrence , Seidel Thomas E. , Sneh Ofer
Published: April 2011

Atomic Layer Deposition (ALD) is an emerging ultra-thin film deposition technique for advanced microelectronics applications. Enabling features of ALD are precise control over film thickness, excellent conformality and relative insensitivity to wafer size. Additionally, ALD allows interface and film engineering that can be utilized to maximize device performance within the minimum feature size requirements. This paper reports on the compositional, structural and electrical properties of engineered Ti-Ta-N composite films grown by ALD at 360°C. For a wide range of composition these Ti-Ta-N films exhibit resistivity from 500 to 2000 μω-cm, high density, and 100 % step coverage. Additionally, the ability to control texture by changing film composition is established. Based on experimental results, an approach to grow Composite Engineered Barriers by ALD (CEBA) is described that could provide a solution to the challenging barrier requirements.
Electromigration Characterization of Damascene Copper Interconnects: Comparison Between CVD Copper and ECD Copper.
Authors: Berger Thierry , Arnaud Lucile , Tartavel Gérard , Lormand Gérard
Published: April 2011

We have characterized the electromigration performance of copper damascene interconnects using moderately and highly accelerated lifetime tests respectively at package and wafer level. Two metallizations have been studied: Chemical Vapor Deposition (CVD) copper deposited on CVD TiN (Process A) and electroplated (ECD) copper deposited on CVD TiN using 90 nm of CVD copper as a seed-layer (Process B). All metallizations were passivated with SiO2. Two line widths have been characterized: 0.6μm and 4μm.

For wide lines, we obtained similar activation energies (Ea) for both metallizations (0.63 for process A and 0.65 eV for process B). For narrow lines, the Ea value is 0.8eV for CVD copper whereas it is higher than 1eV for ECD copper. For wide lines of both metallizations, failure analysis performed with a Scanning Electron Microscope (SEM) gave clear evidences that microstructural gradients have a strong impact on voids and extrusions formation (i.e. that grain boundaries are an active diffusion path in spite of low Ea values). For narrow lines, diffusion at the upper interface is believed to be the main diffusion path.

From the reliability point of view, the extrapolated lifetimes of the metallization including ECD copper are much higher (1 to 2 orders of magnitude depending on the line width) than for CVD copper.
Electrical Characterization of Copper Penetration Effects in the Gate Oxide of MOS Devices
Authors: Mondon François , Cluzel Jacques , Blachier Denis , Morand Yves , Martel Laurent , Reimbold Gilles
Published: April 2011

Copper penetration in thermal oxide was investigated using MOS capacitors by annealing at 450 °C and bias-temperature stress at 250 °C. Copper induces minority carrier generation lifetime decay and oxide leakage current increase. Degradation is enhanced by capacitor biasing, which confirms the role of Cu+ ions. The current-voltage characteristics are consistent with Poole-Frenkel model, showing that electron transport proceeds through traps created in the oxide bulk by copper. When a negative bias is applied, copper traps are removed from oxide near SiO2-Si interface and the leakage current is cancelled but the generation lifetime remains nil, copper contamination of silicon surface being not removed.

None of these effects are observed when the copper gate is separated from oxide by a 10 nm TiN layer, proving that this material is an efficient barrier against copper diffusion at 450°C.
Evolution of Property and Microstructure of P(VDF-TrFE) Copolymers Modified by Irradiation Introduced Defects
Authors: Cheng Z.-Y. , Li Zhimin , Ma Yanyun , Zhang Q. M. , Bateman Fred B.
Published: April 2011

The effect of defects introduced by high-energy electron irradiation on microstructure and properties in poly(vinylidene fluoride- trifluoroethylene) [P(VDF-TrFE)] is reported. In studies of the copolymers, it is found that as defect concentration increases, the material can be changed from a normal ferroelectrics to a relaxor ferroelectrics (RFE) and then to a simple relaxor. Correspondingly, the crystalline morphology changes from a coexistence of polar and non-polar phases to a macroscopically uniform non- polar phase, as revealed by x -ray data. It was observed that the dielectric property in the copolymers with a different amount of defects was well described by the Vogel-Fulcher (V-F) relationship. Based on the experimental data, a critical size, which is the smallest size of crystal with ferroelectric phase, of about 5 nm was obtained for the copolymer. The RFE developed here exhibits a massive electrostrictive strain which is very attractive for many actuator and transducer applications and a high dielectric constant which is attractive for development of high- density energy storage capacitors and electronic packaging.
Direct observation and characterisation of the oxide nanostructured interface resulting from organosilane pre-treatment of aluminium
Authors: Whiting Mark J. , Stolojan Vlad , Rattana Ann , Watts John F.
Published: April 2011

The pre-treatment of aluminium surfaces prior to adhesive bonding and coating processes is of major technological significance. However, the two major commercial pre-treatments, chromic acid and phosphoric acid anodising, both make use of Cr(VI) containing solutions with the attendant problems of waste disposal. The disposal of this harmful solution poses severe environmental problems. Therefore, other environmentally friendly alternatives are being investigated, one of the most popular candidates is the use of one-step pretreatment processes based on organosilane adhesion promoters.

This study examines a model system made from polished aluminium sheet treated with an organosilane; γ-glcidoxypropyltrimethoxysilane (GPS). The interface was characterised by TEM carried out on microtomed sections. The information gained from imaging and Electron Energy Loss Spectroscopy (EELS) analysis revealed a layer of oxide, approximately 70 nm thick. Silicon was found to have been incorporated within this oxide layer. Thus it is suggested that during the curing of the GPS, at elevated temperature, growth of aluminium oxide takes place which gives rise to an Al/O/Si phase.
Conformations in PET-steel laminates studied by FTIR
Authors: Rastogi R. , Vellinga W.P , Asselen O.LJ.v , Meijer H.E.H.
Published: April 2011

PET-steel interfaces were studied with FTIR. Differences in conformations of PET in free standing films and supported films in laminates are attributed to the presence of the PET-metal interface. These differences could be accentuated by varying the physical environment ie. by annealing or mechanically loading both free and supported films.
Mechanical Enhancement Of Nanoporous Low-K Films As Interlayer Dielectrics By Ion Implantation
Authors: Roy Alok Nandini U. , Patel Zubin P. , Mallikarjunan A. , Bakhru H. , Lu T.-M.
Published: April 2011

Thin films of Ultra-Low K materials such as Xerogel (K=1.76) and MSQ (K=2.2) were implanted with argon, neon, nitrogen, carbon and helium with 2 × 1015 cm−2 and 1 × 1016 cm−2 dose at energies varying from 20 to 50 keV at room temperature. In this work we showed that the surface hardness of the porous films is improved five times as compared to the as-deposited porous films sacrificing the dielectric constant up to 15% after implantation (e.g., from 1.76 to 2.0). The hardness persists after 450 °C annealing. It is also shown that implantation can prevent the penetration of chemical gases such as CVD precursors in the Ultra-Low K dielectrics during a CVD process.
The Role of Keto Defect Sites for the Emission Properties of Polyfluorene-Type Materials
Authors: List Emil J.W. , Guentner Roland , Freitas Patricia Scanducci de , Scherf Ullrich
Published: April 2011

In this paper we have identified a dominant degradation mechanism of blue light emitting polyfluorene (PF) type polymers, which turns the desired blue emission colour of these polymers into an undesired blue-green emission. As shown low energy emission band at 2.2–2.3 eV can be identified as the emission from exciton and/or charge trapping keto defect sites (9-fluorenone sites), which in fact can be regarded as emission of a guest (defect) accidentally incorporated into the π-conjugated PF backbone. We present spectroscopic evidence for the formation of keto defect sites in 9-monoalkylated polyfluorenes (PF-a) which are identified as the source of the strong low energy emission band. Furthermore we show that the keto defects can be generated directly during polymer synthesis as show for the PF-a or can be formed as main channel of an (photo- or electro-) oxidative degradation process as show for the 9-bisalkylated PF.
Blood Compatibility of Stainless-Steel and Titanium Immobilized with Alginic Acid Layers
Authors: Yoshioka Tomohiko , Tsuru Kanji , Hayakawa Satoshi , Osaka Akiyoshi
Published: April 2011

γ-Aminopropyltriethoxysilane (γ-APS) was grafted on stainless-steel and titanium substrates, and subsequently alginic acid layer was immobilized on them. Their surfaces were characterized with X-ray photoelectron spectroscopy (XPS) and contact angle measurement. Blood compatibility of thus obtained substrates was evaluated in terms of both the number of the adhered platelets and blood clotting factors for plasma contacted with the substrates such as active partial thromboplastin time (PTT), prothrombin time (PT), and amount of fibrinogen (Fib). The steel and titanium substrates with alginic acid layer did not affect blood clotting factors. In vitro platelet adhesion assay indicated that those substrates adhered less number of platelets than non-treated substrates. Hence the alginic acid immobilization leads to blood compatible surfaces.
The Nanomechanical Effect of Dendrimer Interlayers Underneath Cu Ultrathin Films
Authors: Zhang Junyan , Curry Micheal , Street Shane
Published: April 2011

Two kinds of dendrimers, DAB and PAMAM (with the same terminal groups but different branched repeat units), were chosen as interlayers for Cu ultrathin films deposited on native oxide Si(100) wafers. 10 nm Cu thin films were deposited directly on the dendrimer monolayers by DC sputtering at room temperature. The nanomechanical results show that PAMAM and DAB have significant effects on the properties of the resulting films, with the DAB layer acting as a stiffer ‘spring’, compared to PAMAM, underneath the Cu films. Both dendrimer interlayers lower the hardness of the film, compared to Cu alone; the effect is greater for PAMAM than DAB interlayers. However, the introduction of either dendrimer monolayer significantly increased the elasticity of the Cu film.
SFM and TOF-SIMS Study of Novel Self-Organization phenomena in mixed LB monolayers
Authors: Pignataro B. , Sardone L. , Licciardello A. , Marletta G.
Published: April 2011

Mixed monolayers of dimyristoylphosphatidylcholine (DMPC) and quercetin palmitate (QP) in a molar ratio of 25/75 have been transferred on mica and oxygen plasma cleaned silicon by the Langmuir-Blodgett (LB) technique at different subphase temperatures. Scanning Force Microscopy (SFM) in height, phase and lateral force modes has been employed to investigate the structural and mechanical features at nanoscopic level of these samples. Although the two molecules show a wide range of miscibility at 37 °C, they give rise to phase separation at 10 °C. This last system provides a new example of nanometric scale self-organization. In particular spiral shaped domains rising from the wrapping-up of nanoscopic fiber-like structures have been observed. The high resolution achieved by the use of the dynamic scanning force microscopy operating in the net attractive regime allow to visualize characteristic nanoscopic rupture points along the supramolecular fibers. High mass resolution Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) spectra showed DMPC- as well as QP-related peaks. The ToF-SIMS spectra from the nanostructured samples (10 °C) have been compared with those from the homogeneous ones (37 °C). The phase separated samples provides interesting secondary ions that highlight the QP supramolecular condensation within the fiber-like structures.