bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersion of Lead Zirconate Titanate for Fused Deposition of Ceramics
Authors: McNulty Thomas F. , Shanefield Daniel J. , Danforth Stephen C. , Safari Ahmad
Published: January 2009

A study of the adsorption of several surfactants onto lead zirconate titanate (PZT) powder was performed. The adsorption of oleyl alcohol, stearyl alcohol, oleic acid, and stearic acid onto PZT‐5H powder (surface area = 2.58 m2/g) was measured by thermogravimetric analysis. Toluene was used as a solvent, and the solution concentrations were set at 50.0 g/L. It was found that the stearic acid adsorption onto the PZT‐5H powder was highest, to the extent of 8.1 mg/m2. Trace amounts of stearyl alcohol adsorbed onto PZT, showing an adsorption of 0.8 mg/m2. Both oleyl alcohol and oleic acid showed no measurable adsorption. Once stearic acid was found to be a suitable surfactant for fused deposition of ceramics (FDC), the coating process was studied to further optimize the amount adsorbed. A total of six solution concentrations, varying from 5.0 to 70.0 g/L stearic acid in toluene, were tested. It was found that a solution concentration of 30.0 g/L stearic acid was sufficient to provide maximum coverage of the PZT surface. Increases in concentration beyond 30.0 g/L had no effect on the adsorption of the surfactant. PZT powder coated with stearic acid using this method was compounded with a proprietary thermoplastic binder formulation at 55 vol% PZT. Rheology measurements show that this material exhibits a viscosity adequate for FDC.
Effects of Yttrium Doping α‐Alumina: I, Microstructure and Microchemistry
Authors: Gülgün Mehmet A. , Putlayev Valery , Rühle Manfred
Published: January 2009

The influence of yttrium doping on the microstructure and microchemistry of hot‐pressed α‐alumina was investigated using a combination of electron microscopy techniques. The implications of microstructure and microchemistry on the improved creep behavior of the doped material are discussed. The samples doped only with yttrium had a bimodal grain‐size distribution that was strongly correlated to the frequency and distribution of Y3Al5O12 (YAG) precipitates in the microstructure. Yttrium segregated to most of the grain boundaries, with a normal excess concentration of Gamma= 3.3 ± 0.9 atoms/nm2 at random boundaries. Two types of twin boundaries (Sigma3 and Sigma7) accommodated no yttrium. None of the boundaries or triple‐point junctions contained a glassy grain‐boundary phase. Strong interaction of the grain boundaries and dislocations with YAG precipitates indicated a pinning mechanism by the precipitates. Yttrium doping did not appear to favor formation of special boundaries in α‐alumina.
Surface Roughening and Unstable Neck Formation in Faceted Particles: I, Experimental Results and Mechanisms
Authors: Rankin Janet , Sheldon Brian W.
Published: January 2009

Experimental in situTEM results described by Rankin and Boatner are surprising because they show initial neck formation between two isolated MgO particles, followed by neck rupture. A quantitative assessment of the original images shows that initial neck growth corresponds to material removed from the rounded edges which contact the neck, and that neck rupture transfers material directly from the neck to the adjacent faceted faces. During the initial neck growth process surface diffusion along the rounded edges of the crystals is apparently the dominant mass transport mechanism, and material is not transferred to the faceted faces because of the energy barrier associated with forming a new atomic layer on top of a faceted surface. This energy barrier can apparently be overcome when a curvature reversal at a facet/rough surface boundary creates a step which makes it possible to add one or more new atomic layers to the faceted face(s). This can move material away from the neck, and thus lead to neck rupture.
Processing and Microstructure Development of Titanium Carbide–Nickel Aluminide Composites Prepared by Melt Infiltration/Sintering (MIS)
Authors: Plucknett Kevin P. , Becher Paul F.
Published: January 2009

A combined melt‐infiltration/sintering (MIS) route has been described for the preparation of composites that are based on titanium carbide (TiC) with a ductile nickel aluminide (Ni3Al) “binder” phase. This approach allows control of the Ni3Al content, which can be varied readily in the range of 4–25 vol%. Densities of >98% of the theoretical density have been obtained for composites that have been prepared with Ni3Al contents of ≥8 vol%. Preliminary examination indicates that the infiltration kinetics approximate to parabolic at 1300°C. Compositional analysis of the densified materials indicates only minimal titanium dissolution into the Ni3Al alloy (<6 at.%), with an analyzed carbide composition of TiC0.93. Cubic grain‐growth kinetics are observed for TiC–16‐vol% Ni3Al, with an activation energy of ∼400 ± 60 kJ/mol.
Cyclic Infiltration of Porous Zirconia Preforms with a Liquid Solution of Mullite Precursor
Authors: Lin Yung‐Jen , Chen Yi‐Chi
Published: January 2009

Composites of mullite and zirconia were fabricated via the cyclic infiltration of porous zirconia‐based preforms with a liquid mullite precursor. The maximal amount of mullite precursor that could be infiltrated was dependent primarily on the initial open porosity of the preforms. When a zirconia preform with an initial open porosity of ∼58% was cyclically infiltrated to saturation, the open porosity was reduced to ∼43%, with a median pore diameter of 15 nm. After sintering at a temperature of 1500°C for 2 h, the saturation‐infiltrated zirconia preforms could be densified to ∼98% of the theoretical density. In zirconia samples, infiltrated mullite had a tendency to coalesce into large, elongated grains as the sintering temperature was increased. The presence of infiltrated mullite did not have a significant effect on the zirconia grain structure. The distribution of mullite in the samples was nonuniform, and the distribution profiles varied as the number of infiltration cycles varied. Although the sintered density and hardness showed small improvements after saturation infiltration, the fracture toughness did not increase.
Effect of Processing Parameters on Physical Properties of Cadmium Stannate Thin Films Prepared by a Dip‐Coating Technique
Authors: Tahar Radhouane Bel Hadj , Ban Takayuki , Ohya Yutaka , Takahashi Yasutaka
Published: January 2009

Thin films of dicadmium stannate spinel (Cd2SnO4) were deposited on glass substrates using a dip‐coating technique. The films were transparent to visible light (90%) and electrically conductive. X‐ray diffractometry showed that annealed films consisted of a single cubic spinel phase only when they were prepared from a solution with the composition of Cd:Sn = 2.5 and fired at a temperature of 400°–500°C. The Cd:Sn ratio, the firing temperature, and the post‐deposition annealing sequence were crucial for the formation of a single phase, which is vital to obtain optimal optical and electrical properties. A resistivity as low as 3.3 × 10−4Ω·cm could be obtained after annealing.
Effect of Vacuum Heat Treatment on Electron‐Beam‐Irradiation‐Cured Polycarbosilane Fibers
Authors: Shimoo Toshio , Ito Masahiro , Okamura Kiyohito , Takeda Michio
Published: January 2009

Electron‐beam‐cured polycarbosilane fibers were heat‐treated at 673–1773 K in a tube evacuated to 1.3 × 10−1 Pa and then exposed at 1873 K in argon. The effect of vacuum heat treatment on improving the high‐temperature stability of low‐oxygen SiC fibers was investigated by examining gas evolution, grain growth, surface composition, tensile strength, and morphology. The fibers heat‐treated at <1173 K lost strength, because of the vigorous generation of residual hydrogen. A minute amount of oxygen in the atmosphere caused the active oxidation of SiC during heat treatment at >1673 K, resulting in severe strength degradation for the as‐heat‐treated fibers. Vacuum heat treatment at 1573 K provided the best characteristics in low‐oxygen SiC fibers.
Improved Resistance to Damage of Silicon Carbide‐Whisker‐Reinforced Silicon Nitride‐Matrix Composites by Whisker‐Oriented Alignment
Authors: Wang Chang‐an , Huang Yong , Xie Zhipeng
Published: January 2009

The effects of whisker‐oriented alignment on resistance to damage of SiC(w)/Si3N4 composites have been investigated by the Vickers indentation method and R‐curve behavior. It is shown that increasing the degree of whisker‐oriented alignment decreases the lengths of Vickers impressions and indentation cracks. The results exhibit rising R‐curve behaviors for the SiC(w)/Si3N4 composites with different degree of whisker‐oriented alignment. Moreover, the initial crack length ci, the threshold of crack growth resistance Ki, and the upper bound of crack growth resistance K∞ change regularly with increasing degree of whisker‐oriented alignment. All results suggest that the whisker‐oriented alignment improves the resistance to damage of the composites, resulting in a more reliable and usable composite.
Defect Chemistry and Microstructure of Hydrothermal Barium Titanate
Authors: Hennings Detlev F. K. , Metzmacher Christoph , Schreinemacher B. Seriyati
Published: January 2009

Hydrothermal powders of BaTiO3 and (Ba,Ca)(Ti,Zr)O3 contain large amounts of protons in the oxygen sublattice. The proton defects are compensated by vacancies on metal sites. When the powder is annealed, water is released and the point defects disappear in the temperature range of 100°–600°C. Metal and oxygen vacancies combine to small nanometer‐sized intragranular pores. At temperatures of >800°C, the intragranular pores migrate to the grain boundaries and disappear. In multilayer ceramic capacitors that have been prepared from hydrothermal powders, the intragranular pores are preferentially collected at the inner electrodes, which results in “bloating,” cracks, and delamination.
Silicon Carbide Films by Laser Pyrolysis of Polycarbosilane
Authors: Colombo Paolo , Martucci Alessandro , Fogato Oscar , Villoresi Paolo
Published: January 2009

Thin films of polycarbosilane were deposited on Si and SiO2 substrates. Instead of conventional oven annealing (high temperatures, inert atmosphere), laser pyrolysis was used to achieve the polymer‐to‐ceramic conversion. In some conditions, especially when laser radiation absorption was enhanced by depositing a carbon layer on the surface of as‐deposited films or by embedding graphite particles, this processing method yielded SiC ceramic coatings, without damaging the substrate. Processing in air or low vacuum did not result in oxidized coatings, contrary to what happens for oven pyrolysis. Laser‐converted films were similar to oven‐heated films processed at 1000° to 1200°C.
Synthesis of Porous Ceramics with Complex Pore Structure by Freeze‐Dry Processing
Authors: Fukasawa Takayuki , Ando Motohide , Ohji Tatsuki , Kanzaki Shuzo
Published: January 2009

Porous ceramics with complex pore structure were synthesized by a freeze‐dry process. Freezing‐in of a water‐based ceramics slurry was done while controlling the growth direction of the ice. Sublimation marks of the ice were generated by drying under reduced pressure. Porous ceramics having a complex pore structure were obtained by sintering the green body: aligned macroscopic open pores contained micropores in their internal walls. The pore structure was substantially affected by the starting slurry concentration and sintering temperature. The pore formation mechanism is discussed in relation to these effects.
Packing Density of Binary Mixtures of Wet Spheres
Authors: Zou Rui‐Ping , Feng Chang‐Lin , Yu Ai‐Bing
Published: January 2009

An experimental study of the packing of binary mixtures of coarse spheres with the addition of water has been conducted. The results indicate a similarity between dry and wet packings, either in the relationship between the packing density and the moisture content or in the relationship between the packing density and the particle‐size distribution. The Westman equation is used to describe the wet packing after necessary modification. The approach is verified by the good agreement between the calculated and measured packing densities.
Characterization of Lanthanum‐Doped Barium Titanate Ceramics Using Impedance Spectroscopy
Authors: Morrison Finlay D. , Sinclair Derek C. , West Anthony R.
Published: January 2009

The electrical properties of two single‐phase, lanthanum‐doped BaTiO3 compositions, x= 0.03 and x= 0.20, in Ba1–xLaxTi1–x/4O3 were investigated by impedance spectroscopy after heat treatment in oxygen, argon, and air at 1350°C. Samples heated in oxygen were electrically insulating, whereas those heated in argon lost oxygen and were semiconducting at room temperature, irrespective of x. Samples heated in air showed intermediate electrical properties and also were electrically inhomogeneous; the two compositions showed different electrical behaviors, and a model for each, based on oxygen nonstoichiometry within the ceramics, is proposed. Oxygen deficiency in samples sintered in air was avoided by heating at 1200°C, instead of 1350°C. Alternatively, oxygen lost from ceramics heated in air at 1350°C was regained by postannealing in oxygen at 1350°C.
Interactions and Chemistry of Defects at the Grain Boundaries of Ceramics
Authors: Han Joo‐Hwan , Kim Doh‐Yeon
Published: January 2009

A thermodynamic approach is used to derive a defect chemistry formulation at the grain boundary of an ionic solid. Considering the elastic and/or electrostatic interactions between charged defects, the equilibrium electrostatic potential and the concentration of charged defects at the grain boundaries can be quantitatively predicted. The obtained result has general applicability at all levels of defect concentrations. Defect concentration at the boundary has been determined to critically depend on the interactions between defects, electrostatic potential, and segregation. These interactions, either acting individually or coupling with each other, lead to a nonuniform defect distribution near the grain boundary. Calculations also show that the grain‐boundary segregation of an aliovalent solute is greatly affected by doping through the electrostatic or elastic interactions. The variation of the grain‐boundary characteristics with the processing parameters, such as dopant concentration and temperature, is discussed in relation with the proposed model.
Thermal Stability of Polycarbosilane‐Derived Silicon Carbide Fibers under Reduced Pressures
Authors: Shimoo Toshio , Takeuchi Hiroshi , Okamura Kiyohito
Published: January 2009

Three types of polycarbosilane‐derived SiC fibers—Nicalon, Hi‐Nicalon, and Hi‐Nicalon S—were exposed at temperatures of 1573–1773 K under a reduced pressure of 1.3 Pa. The thermal stability of the fibers was investigated through examinations of the gas evolution, grain growth, specific resistivity, fiber morphology, and tensile strength. The thermal decomposition of the silicon oxycarbide phase began at 1523 K; then, active oxidation of the β‐SiC crystallites occurred at >1673 K. The active oxidation caused serious damage to the fiber structure, which resulted in significant degradation of the fiber strength. Hi‐Nicalon had a tensile strength of ∼0.5 GPa after exposure at 1773 K, although Nicalon and Hi‐Nicalon S fibers completely lost their strength, even after exposure at 1673 K. Hi‐Nicalon fiber had relatively good thermal stability under reduced pressure.
Hydration Characteristics of Portland Cement after Heat Curing: I, Degree of Hydration of the Anhydrous Cement Phases
Authors: Yang Renhe , Sharp John H.
Published: January 2009

The degree of hydration of the four major anhydrous cement phases in three U.K. portland cement mortars has been observed during the period of water storage at room temperature after an initial short‐term heat cure. Such a heat cure at 85° or 100°C for 12 h generally accelerated the initial hydration of the four major anhydrous minerals in portland cement. Subsequent retardation of the degree of hydration of the alite, tricalcium aluminate, and ferrite phases was observed when these heat‐cured mortars were stored at ambient temperature. General similarity but some differences in hydration behavior were observed between the three cements. The hydration of belite in the heat‐cured mortars during storage at room temperature produced porous inner products that favored deposition of ettringite and reduced the risk of expansive ettringite formation. The substantial retardation in hydration of the aluminate‐bearing phases, especially the ferrite phase, during the storage at room temperature raised the overall SO3/Al2O3 ratio of the cement hydrates formed, bringing about a potential for ettringite formation and hence the risk of expansion through delayed ettringite formation.
Equilibrium Amorphous Silicon–Calcium–Oxygen Films at Interfaces in Copper–Alumina Composites Prepared by Melt Infiltration
Authors: Scheu Christina , Dehm Gerhard , Kaplan Wayne D.
Published: January 2009

The microstructure of copper–alumina (Cu‐Al2O3) composites that have been prepared via the melt infiltration of liquid copper into porous alumina preforms was studied in detail, using various transmission electron microscopy (TEM) techniques. Two different samples—with open pore diameters of 0.2 and 0.8 μm—were investigated. For both specimens, a single crystalline copper network that extended throughout the open porosity of the alumina preform was observed. An amorphous glass phase that contained silicon and calcium was observed at the Al2O3/Cu/Al2O3 triple junctions. The diameters of these amorphous pockets, which were strongly faceted along the Al2O3 grains, were up to 20 and 100 nm for the initial pore sizes of 0.2 and 0.8 μm, respectively. A glass phase that contained silicon and calcium also was present at the Cu/Al2O3 interfaces, whereas the Al2O3 boundaries remained dry. Detailed high‐resolution transmission electron microscopy investigations have shown that the interfacial glass phase at the Cu/Al2O3 interfaces exhibited a uniform equilibrium film thickness along the interface region. However, the interfacial film thickness was dependent on the orientation of the Al2O3 grain, and its value varied from 0.4 nm for Al2O3 rhombohedral‐plane termination ((1¯012)) up to 1 nm for Al2O3 basal‐plane termination ((0001)).
Seeding of the Reaction‐Bonded Aluminum Oxide Process
Authors: Suvaci Ender , Messing Gary L.
Published: January 2009

The effect of the initial α‐Al2O3 particle size in the reaction‐bonded aluminum oxide (RBAO) process on the phase transformation of aluminum‐derived γ‐Al2O3 to α‐Al2O3, and subsequently densification, was investigated. It has been demonstrated that if the initial α‐Al2O3 particles are fine (∼0.2 μm, i.e., 2.9 × 1014γ‐Al2O3 particles/cm3), then they seed the phase transformation. The fine α‐Al2O3 decreases the transformation temperature to ∼962°C and results in a finer microstructure. The smaller particle size of the seeded RBAO decreases the sintering temperature to as low as ∼1135°C. The results confirm that seeding can be utilized to improve phase transformations and densification and subsequently to tailor final microstructures in RBAO‐derived ceramics.
In Situ Ultraviolet Raman Study on the Phase Transition of Hafnia up to 2085 K
Authors: Fujimori Hirotaka , Yashima Masatomo , Kakihana Masato , Yoshimura Masahiro
Published: January 2009

We have recently demonstrated that the Raman scattering through ultraviolet (UV) excitation is eminently well suited for in situ investigation of materials at high temperatures up to 1773 K. Here we report successful Raman measurements of HfO2 up to 2085 K, using only a 100 mW power of UV laser line. The monoclinic‐to‐tetragonal transformation finished around 2080 K on heating, while the monoclinic phase appeared at 2018 K on cooling.
High‐Temperature Morphological Evolution of Lithographically Introduced Cavities in Silicon Carbide
Authors: Narushima Takayuki , Glaeser Andreas M.
Published: January 2009

Internal cavities of controlled geometry and crystallography were introduced in 6H silicon carbide single crystals by combining lithographic methods, ion‐beam etching, and solid‐state diffusion bonding. The morphologic evolution of these internal cavities (negative crystals) in response to anneals of up to 128 h duration at 1900°C was examined using optical microscopy. Surface energy anisotropy and faceting had a strong influence on the geometric and kinetic characteristics of evolution. Decomposition of {1210} cavity edges into {101x} facets was observed after 16 h anneals, indicating that {1210} faces are not components of the Wulff shape. The shape evolution kinetics of penny‐shaped cavities were also investigated. Experimentally observed evolution rates decreased much more rapidly with those predicted by a model in which surface diffusion was assumed to be rate limiting. This suggested that the development of facets and the associated loss of ledges and terraces during the initial stages of evolution resulted in an evolution process limited by the nucleation rate of attachment/detachment sites (ledges) on the facets.
Effect of the Interparticle Pair Potential on the Rheological Behavior of Zirconia Powders: II, The Influence of Chem‐Adsorbed Silanes
Authors: Klein Sascha , Fisher Matthew , Franks George , Colic Miroslave , Lange Fred
Published: January 2009

The influence of two bifunctional aminosilanes, N‐(triethoxysilylpropyl)‐O‐polyethylen oxid urehtan (PEG‐silane) and N‐(3‐triethyoxsilylpropyl) gluconamid (Glucol‐silane), on the rheological behavior of aqueous zirconia (solid solution with 3 mol% Y2O3) powder slurries and consolidated bodies was investigated. Adsorption of the silanes was determined with viscosity measurements. The influence of tetramethylammonium (TMA) chloride added to dispersed slurries to produce weakly attractive particle networks, formulated with the aminosilane reacted powders was investigated. Bodies were consolidated by filtration at different applied pressures. Viscosity vs shear rate behavior, and consolidated body rheology, were determined for slurries formulated at different pH values and different salt contents. The Glucol‐silane coated powder had a different isoelectric point (pH ∼8.5) relative to the unreacted (pH ∼7.5) and PEG‐silane coated powders (pH ∼7). Dispersed slurries with Newtonian behavior could be formulated for the following conditions: unreacted powder = pH 11, PEG‐silane coated powder = pH 10, and Glucol‐silane coated powder = pH 6. Bodies with the highest relative density (∼51%) were produced from dispersed slurries (uncoated and coated); their relative density was nearly pressure insensitive. The relative density of consolidated bodies produced from slurries with an attractive particle network (formulated either at the isoelectric point or dispersed with added salt) was pressure sensitive. Bodies consolidated with the weakly attractive particle networks exhibited a critical relative density that separated the body's plastic and brittle behavior. The highest critical relative density (47%) was achieved for bodies consolidated with salt‐added, dispersed slurries formulated with the longest aminosilane molecule, which produced the weakest attractive particle network. Bodies that exhibited a claylike flow stress (∼0.1 MPa) could be formulated with the shorter aminosilane molecule, whereas the longer aminosilane molecule produced a fluidlike body without a significant yield stress.
Microstructure and Mechanical Properties of Silicon Nitride Materials Fabricated from SHS Powders
Authors: De Pablos Angel , Bermudo Joaquin , Osendi Maria Isabel
Published: January 2009

Two different silicon nitride powders, one produced by self‐propagating high‐temperature synthesis (SHS) and one commercial, have been equally processed to obtain dense materials. Y2O3 powders as a sintering aid and hot‐pressing techniques were used to process the materials. The fracture toughness and strength of the materials prepared have been evaluated and the results comparatively discussed as a function of the microstructure, with special emphasis on the characteristics of the initial powders.
Influence of Tetragonality on Tetragonal‐to‐Monoclinic Phase Transformation during Hydrothermal Aging in Plasma‐Sprayed Yttria‐Stabilized Zirconia Coatings
Authors: Yasuda Kazuhiro , Goto Yasuhiro , Takeda Hiromitsu
Published: January 2009

The influence of tetragonality, which is defined as the lattice parameter ratio c/a, on the tetragonal‐to‐monoclinic phase transformation during hydrothermal aging was investigated in yttria‐stabilized zirconia coatings. The yttria content was adjusted in the range of 4–8 mass% (denoted as xYZ, where x= 4–8 and YZ represents the yttria‐stabilized zirconia). The tetragonality of the zirconia in the as‐sprayed coatings was less than that in the powders. To change the tetragonality for each yttria content, the coatings were annealed at 1273 K before aging. Without annealing, the phase transformation was prevented only in 8YZ. When annealing was applied, an increase of the tetragonality (i.e., recovery of the tetragonality) was observed, and transformation during hydrothermal aging was also suppressed in 6YZ. It was concluded that the increase in tetragonality that occurred without a change in the yttria content was suggested to be caused by the lattice relaxation of the tetragonal phase, and this relaxation is believed to cause a reduction of the critical yttria concentration, thus preventing the phase transformation.
Temperature and Stress Distributions in a Hollow Cylinder of Functionally Graded Material: The Case of Temperature‐Independent Material Properties
Authors: Awaji Hideo , Sivakumar Ramasamy
Published: January 2009

We have presented a numerical technique for analyzing one‐dimensional transient temperature distributions in a circular hollow cylinder that was composed of functionally graded ceramic–metal‐based materials, without considering the temperature‐dependent material properties. The functionally graded material (FGM) cylinder was assumed to be initially in a steady state of gradient temperature; the ceramic inner surface was exposed to high temperature, and the metallic outer surface, which was associated with its in‐service performance, was exposed to low temperature. Then, the FGM cylinder was cooled rapidly on the ceramic surface of the cylinder, using a cold medium. The transient temperature and related thermal stresses in the FGM cylinder were analyzed numerically for a model of the mullite–molybdenum FGM system. The technique for analyzing the temperature distribution is quite simple and widely applicable for various boundary conditions of FGMs, in comparison with methods that have been proposed recently by other researchers.
Solubility of Platinum and Rhodium in Lime–Alumina–Silica Melts at 1700 K
Authors: Dable Pierre , Allibert Michel , Poignet Jean Claude , Amosse Jean
Published: January 2009

Three oxide melts of composition 10‐20‐70, 30‐13‐57, and 40‐20‐40 (wt%) in the ternary system CaO–Al2O3–SiO2 were equilibrated at 1700 K in platinum or platinum–rhodium boats, under oxygen partial pressures (PO2) ranging from 10−13 to 1 atm, and fixed by various gaseous mixtures (H2/H2O, CO/CO2, and Ar/O2). The melts were analyzed for platinum and rhodium content after quenching. The complex dependence of solubility of these elements with PO2 was explained by their speciation. Chronopotentiometric measurements confirmed the passivation of the metallic boats. For increased PO2, this speciation followed the series Pt, PtO, PtO2 or RhO for the solid phases covering the metallic boats and Pt0, Pt2+, Pt4+, Pt6+ or Rh0, Rh2+, Rh3+, Rh4+ in solution in the oxide melt. The predominance diagrams were determined for the three compositions in the ternary system.
Microstructure of a Molybdenum Nitride Layer Formed by Nitriding Molybdenum Metal
Authors: Nagae Masahiro , Yoshio Tetsuo , Takemoto Yoshito , Takada Jun
Published: January 2009

For pure molybdenum nitrided at 1373 K in NH3 gas, microstructural observations of a molybdenum nitride layer were conducted through a transmission electron microscope. The molybdenum nitride layer consisted of two molybdenum nitrides: an outer one of γ‐Mo2N and an inner one of β‐Mo2N. A great number of (011)[01] type twins were observed in the β‐Mo2N phase, whereas the microstructure of the γ‐Mo2N phase was almost free from lattice defects except for slightly observed {111}〈112〉 type twin.
Generalized Titanate Ceramic Waste Form for Advanced Purex Reprocessing
Authors: Maddrell Ewan R.
Published: January 2009

Alternative dissolution processes for spent nuclear fuel lead to highly active waste streams rich in zirconium, iron, chromium, and nickel at levels that vary with fuel assembly design. A titanate ceramic phase assemblage has been developed with the flexibility to accommodate these variations in waste stream composition. Waste loadings range from 42 to 50 wt%. Leach rates are comparable to those from Synroc C.
Effect of Nb2O5/ZnO Addition on Microwave Properties of (Zr0.8Sn0.2)TiO4 Ceramics
Authors: Park Yong Hwan , Ryu Ji Man , Shin Moo Young , Ko Kyung Hyun , Kim Dong Wan , Hong Kug‐Sun
Published: January 2009

The effects of Nb2O5 and ZnO addition on the dielectric properties, especially the quality factor, of (Zr0.8Sn0.2)TiO4 (ZST) ceramics were investigated in terms of the sintered density acquired by the zinc. For ZST ceramics with 2 mol% added ZnO, the relative density of the samples decreased with >0.5 mol% addition of Nb2O5. On the other hand, for samples with 6 mol% added ZnO, the relative density remained >97%, even when the amount of Nb2O5 was increased to 2.0 mol%. When >0.5 mol% Nb2O5 was added, both the quality factor and the dielectric constant exhibited similar trends with sintered density. The ZST ceramics with 6 mol% added ZnO, especially, still manifested a quality factor >40 000 and a dielectric constant of 37, even when the amount of Nb2O5 was increased, values that are not explainable by the previously suggested electronic defect model.
Tribological Properties of Unidirectionally Aligned Silicon Nitride
Authors: Nakamura Masateru , Hirao Kiyoshi , Yamauchi Yukihiko , Kanzaki Shuzo
Published: January 2009

A silicon nitride ceramic with unidirectionally aligned β‐Si3N4elongated grains (UA‐SN) was fabricated by sintering the extruded Si3N4green body with a small amount of rodlike β‐Si3N4seed. The effect of anisotropy in microstructure on tribological properties was investigated, compared with a fine‐grained Si3N4without seed. Block‐on‐ring tests without lubricant were conducted at sliding speeds of 0.15 and 1.5 m/s, with a normal load of 5 N and a sliding distance of 75 m, using the UA‐SN and Si3N4without seeds as block specimens and commercially supplied Si3N4as ring specimens. For UA‐SN, tribological properties were evaluated in three directions with respect to the grain alignment: the plane normal to the grain alignment, and in the direction parallel to or perpendicular to the grain alignment in the side plane. For both sliding speeds, the plane normal to the grain alignment exhibited the highest wear resistance, and the worn surface of this plane was quite smooth, in contrast to the other specimens whose surfaces were irregular owing to grain dropping. It is considered that the high wear resistance achieved in this plane is attributable to the inhibition of crack propagation along the sliding surface by the stacked elongated grains normal to the sliding surface.
Determination of Positions of Zeolitic Calcium Atoms and Water Molecules in Hydrothermally Formed Aluminum‐Substiqtuted Tobermorite‐1.1nm Using Synchrotron Radiation Powder Diffraction Data
Authors: Yamazaki Satoru , Toraya Hideo
Published: January 2009

The crystal structure of hydrothermally formed Al‐substituted tobermorite‐1.1nm (Ca4.9Si5.5Al0.5O16.3(OH)0.7·5H2O) has been analyzed using synchrotron radiation powder diffraction data. Crystallographic positions of a zeolitic Ca atom and three water molecules in the channel of the framework were determined by the Monte Carlo method and subsequent Rietveld refinement. The Ca atom splits into two sites at a distance of 0.161 nm apart, and it is coordinated with the three water molecules and the three oxygen atoms belonging to the framework. Al atoms preferably substitute a part of the Si atoms at the “bridging SiO4” tetrahedra rather than at those of the “chain middle group SiO4” tetrahedra.
Preparation of Zirconia Whiskers from Zirconium Hydroxide in Sulfuric Acid Solutions under Hydrothermal Conditions at 200°C
Authors: Murase Yoshio , Kato Etsuro
Published: January 2009

Mixtures of Zr(OH)4 and ZrO2 particles, ∼10 nm in size, were hydrothermally treated in 0.25–1.5 mol/L H2SO4 solutions at a temperature of 200°C. After 3 h, very short ZrO2 fibers, 10–30 nm in length, were obtained, with no other zirconium compounds observed. The particles grew with treatment time and resulted in whisker particles. In a higher concentration (3 mol/L) H2SO4 solution, ZrO2 whiskers were not obtained, and clear solutions resulted with the starting ZrO2 particles remaining. It was concluded that Zr(OH)4 was useful as a starting material and that nanosized ZrO2 particles served as seed crystals for whisker formation.
Effect of Magnesium Ions on the Adsorption of Poly(acrylic acid) onto Alumina
Authors: Sun Jing , Bergström Lennart , Gao Lian
Published: January 2009

The adsorption isotherms of poly(acrylic acid) (PAA) onto alumina powder have been determined as a function of pH, ionic strength, and magnesium‐ion concentration. The adsorption of PAA is strongly enhanced by magnesium ions in alkaline media but less affected under acidic conditions. The adsorption isotherms display a maximum when PAA is fully complexed with magnesium ions in the solution, corresponding to a ratio of 0.25 ± 0.05 [Mg2+]/[acrylic acid monomer]. The decrease in adsorbed amount with an increase in PAA concentration at constant magnesium‐ion concentration is related to a decrease in the complexation ratio.
Residual Stress Induced R‐Curves in Laminar Ceramics That Exhibit a Threshold Strength
Authors: Rao Masa P. , Rödel Jürgen , Lange Fred F.
Published: January 2009

A stress intensity (K) function describing the extension of a crack through bounding compressive layers has been experimentally verified using two methods. For one method the crack length was measured using a replicating technique; in the other, the crack length was continuously measured insitu with an optical microscope during loading. In both, cracks were observed to propagate in a stable, nearly straight path across the compressive layer with increasing applied stress. Catastrophic failure was observed when the crack fully extended across the compressive layers at an applied stress predicted and described as the threshold stress. This behavior and agreement were valid only when either the compressive stress or the thickness of the compressive layer was small.
Accuracy of an electronic apex locator in primary teeth with root resorption
Authors: Angwaravong O. , Panitvisai P.
Published: January 2009

Aim  To evaluate whether root resorption of primary molar teeth affects the accuracy of the Root ZX apex locator and to compare the Root ZX at different meter readings with direct canal measurement.

Methodology  Sixty extracted primary molar teeth with root resorption affecting one sixth to one third of root length were used. The teeth were embedded in an alginate model. A K‐type file was used in association with a Root ZX apex locator to measure canal length. Measurements were recorded using the Root ZX meter reading ‘Apex’ and ‘0.5 bar’. Actual tooth length was measured with a K‐file to the major foramen. All measurements were read under a stereomicroscope at 15× magnification. The deviation of the Root ZX measurement from the actual canal length was determined.

Results  Mean differences between Root ZX length meter reading ‘Apex’ and actual length were 0.01 ± 0.23 mm whereas mean differences between Root ZX length meter reading ‘0.5 bar’ and actual length were −0.33 ± 0.30 mm. The Root ZX was 96.7% accurate to within ± 0.5 mm of the apical foramen when compared with the actual canal length of primary molars with root resorption.

Conclusions  Using a criterion of ± 0.5 mm, the accuracy of the Root ZX was high and not affected by root resorption. When compared with direct canal measurement, the error in locating the apical foramen was smaller with measurement at meter reading ‘Apex’ than meter reading ‘0.5 bar’.
The effect of resin‐based sealers on fracture properties of dentine
Authors: Jainaen A. , Palamara J. E. A. , Messer H. H.
Published: January 2009

Aim  To determine whether resin‐based sealer cements are able to strengthen root dentine, as measured by work of fracture (Wf), micro‐punch shear strength (MPSS) and resistance to vertical root fracture (VRF).

Methodology  One hundred and twenty extracted premolar teeth were randomly assigned amongst four treatments before testing: intact, root canals prepared but unfilled, or root filled using epoxy‐ or urethane dimethacrylate (UDMA)‐based sealer (plus core material). Samples were then prepared for measuring Wf, MPSS or VRF using standard test procedures. Data were analyzed using one‐way anova with significance set at P < 0.05.

Results  For all three tests, root canals filled using epoxy resin‐based sealer were not statistically significantly different compared with UDMA resin (P = 1 for Wf, P = 0.7 for MPSS and P = 0.12 for VRF), or different from both sound and prepared dentine (P > 0.05). There was also no significant difference between sound dentine and prepared dentine for both Wf (P = 0.92) and resistance to VRF (P = 1).

Conclusions  Neither epoxy nor UDMA resins used as sealer cements enhanced fracture resistance of root dentine when placed within root canals of extracted teeth.
Enzymatic treatments reveal differential capacities for xylan recognition and degradation in primary and secondary plant cell walls
Authors: Hervé Cécile , Rogowski Artur , Gilbert Harry J. , Paul Knox J.
Published: January 2009

The capacity of four xylan‐directed probes (carbohydrate‐binding modules CfCBM2b‐1‐2 and CjCBM15; monoclonal antibodies LM10 and LM11) to recognize xylan polysaccharides in primary and secondary cell walls of tobacco stem sections has been determined. Enzymatic removal of pectic homogalacturonan revealed differential recognition of xylans in restricted regions of cortical primary cell walls. Monoclonal antibody binding to these exposed xylans was more sensitive to xylanase action than carbohydrate‐binding module (CBM) binding. In contrast, the recognition of xylans by CBMs in secondary cell walls of the same organ was more sensitive to xylanase action than the recognition of xylans by the monoclonal antibodies. A methodology was developed to quantify indirect immunofluorescence intensities, and to evaluate xylanase impacts. The four xylan probes were also used to detect xylan populations in chromatographic separations of solubilized cell wall materials from tobacco stems. Altogether, these observations reveal the heterogeneity of the xylans in plant cell walls. They indicate that although CBM and antibody probes can exhibit similar specificities against solubilized polymers, they can have differential capacities for xylan recognition in muro, and that the access of molecular probes and enzymes to xylan epitopes/ligands also varies between primary and secondary cell walls that are present in the same organ.
Association of the HLA‐DPB1*0501 allele with anti‐aquaporin‐4 antibody positivity in Japanese patients with idiopathic central nervous system demyelinating disorders
Authors: Matsushita T. , Matsuoka T. , Isobe N. , Kawano Y. , Minohara M. , Shi N. , Nishimura Y. , Ochi H. , Kira J.
Published: January 2009

There are two subtypes of multiple sclerosis (MS) in Asians: the opticospinal (OSMS) form that shows a selective involvement of the optic nerve and the spinal cord and the conventional (CMS) form that has disseminated lesions in the central nervous system including the cerebrum, cerebellum and brainstem. Both show distinct human leukocyte antigen (HLA) class II associations. OSMS has similar features to the relapsing form of neuromyelitis optica (NMO) in Western populations. Recently, it was shown that antibodies to aquaporin‐4 (AQP4) are specifically detected in NMO patients and in some Japanese patients with OSMS or recurrent optic neuritis or myelitis. To clarify the immunogenetic background of anti‐AQP4 antibody production, we studied HLA‐DRB1 and ‐DPB1 gene polymorphisms in anti‐AQP4 antibody‐positive and ‐negative patients with idiopathic demyelinating diseases, such as MS, recurrent optic neuritis and recurrent myelitis. The phenotypic frequency of the HLA‐DPB1*0501 allele was significantly increased in anti‐AQP4 antibody‐positive patients (89.5%, odds ratio = 4.8; 95% confidence interval = 1.6–14.3, n = 38, Pcorr = 0.032) compared with controls (64.0%, n = 125) but not in either anti‐AQP4 antibody‐negative OSMS (75.0%, n = 32) or CMS (69.2%, n = 52) patients. There was no significant correlation between any HLA‐DRB1 allele and the existence of anti‐AQP4 antibody. These findings suggest that the emergence of anti‐AQP4 antibody is reinforced by the presence of the HLA‐DPB1*0501 allele in Japanese.
Clinicopathological study of early progressive multifocal leukoencephalopathy incidentally found in a schizophrenia patient
Authors: Oshima Kenichi , Tsuchiya Kuniaki , Niizato Kazuhiro , Akiyama Haruhiko , Arai Tetsuaki , Nagashima Kazuo
Published: January 2009

A 58‐year‐old Japanese man developed psychomotor excitement and hallucinatory paranoia at age 53, which gradually developed to residual schizophrenia. He was administered various common tranquilizers until death. Myelodysplastic syndrome was noted 10 months before death. A routine autopsy was performed. The brain weighed 1365 g, and macroscopic observation revealed no remarkable findings. However, microscopic examination disclosed cells with enlarged and basophilic nuclei, and unusual astrocytes in the demyelinated foci, especially at the corticomedullary junctions in the temporal and occipital lobes. On the other hand, the white matter was relatively intact. Immunohistochemical analysis using anti‐JC virus protein, VP‐1 antibody, demonstrated JC virus‐infected cells in not only abnormal glial cells and neurons but also normal‐looking cells, which are suggestive of progressive multifocal leukoencephalopathy (PML). Immunostaining for GFAP revealed severe gliosis and some scattered abnormal enlarged nuclear cells in the lesions. Some clusters of CD8‐positive lymphocytes were seen, which kill infected cells. PML could be considered a short‐term disease preceding death, as “incidental PML” in this case. This is a rare autopsy case of early PML occurring in a schizophrenia patient with PML.
Factors associated with seclusion in a statewide forensic psychiatric service in Australia over a 2‐year period
Authors: Thomas Stuart D.M. , Daffern Michael , Martin Trish , Ogloff James R.P. , Thomson Lindsay D.G. , Ferguson Murray
Published: January 2009

Despite seclusion being described as one of the most ethically‐ and legally‐controversial management options available, it remains a widely‐used clinical strategy for managing disruptive, aggressive, and violent behaviour. This study sought to determine how frequently seclusion was used, the common characteristics of those secluded and not secluded, and the degree to which the Level of Service Inventory – Revised: Screening Version (LSI‐R: SV) could predict seclusion. The study was retrospective, covering the first 2 years of operation of a statewide forensic psychiatry hospital in Victoria, Australia. Data were collected from individual case files, electronic databases, and paper copies of records pertaining to violent incidents and episodes of seclusion. Eighty five (44%) of the 193 patients admitted during this period were secluded. Those secluded were significantly younger and had a more established psychiatric history. LSI‐R: SV scores were significantly and positively associated with being secluded. A statistical model containing three LSI‐R: SV items, along with age on admission and psychiatric history, achieved an area under the curve of 0.74. Seclusion is used on a regular basis in response to a range of different forms of aggressive behaviour of different severity. The LSI‐R: SV demonstrated moderate‐to‐good accuracy in predicting seclusion and warrants further research using detailed prospective methodologies.
Evaluation of a new mental health liaison role in a rural health centre in Rocky Mountain House, Alberta: A Canadian story
Authors: Brinkman Karen , Hunks Dwight , Bruggencate Gloria , Clelland Steve
Published: January 2009

This paper describes the evaluation of a mental health liaison (MHL) role in a rural community in Alberta, Canada. The role provides advocacy, education, indirect and direct client intervention, and follow up. It was developed to eliminate gaps in mental health care and build collaborative cultures between the local hospital, physicians' offices, mental health clinics, and community agencies. Obtaining stakeholder feedback was an important step in assessing initial service impact while providing directions for role refinement and future programme development. A total of 116 questionnaires were distributed to physicians, hospital staff, and community mental health assessing stakeholder perception relating to various functions of the MHL. A 50% (n = 58) response rate was achieved with broad representation from different partners, including 75% of local physicians. The majority of respondents positively perceived the roles, functions, and impact of the MHL, including relationship development across the hospital community, improved access to services, and perceived improved client outcomes. The results reinforced that the MHL service meets a previously unmet need in this rural setting. Findings are being used to refine roles, provide local learning and resource development, understand issues relating to programme development in other areas, and develop client level outcomes relating to the services delivered.
An Array of Online Teaching Tools
Authors: Bush Stephen , Menzies Gordon , Thorp Susan
Published: January 2009

The Internet offers a huge array of teaching resources for statistics. Here we present a selection of engaging Web‐based tools, ranging from class surveys to individual simulation experiments.
BEYOND HEURISTICS: APPLYING SCENARIOS TO EUROPEAN TERRITORIAL DEVELOPMENT
Authors: DAMMERS ED , EVERS DAVID
Published: January 2009

Scenarios, unlike forecasts or prognoses, do not seek to predict future events. Instead, the intent is to understand how the future is produced by examining a number of possible developmental pathways. These pathways are created by adjusting a limited number of variables within a particular cause‐effect chain of events. The insights generated by the scenario method not only produce knowledge about driving forces but also regarding the capacity to change the future. A scenario study carried out by the ESPON programme on the territorial development of Europe has not only cast light on how the spatial structure of Europe is likely to evolve, and identified a number of challenges which any future spatial policy will need to address. These insights have since made their way into a number of important policy documents, including the Territorial Agenda.
ANALYSIS OF POLICY CHANGES IN THE SEAFOOD PROCESSING INDUSTRY IN VIETNAM
Authors: Hong Dao Thanh , Le Quan Vu
Published: January 2009

Abstract.  This paper examines firms’ competitiveness in the seafood processing industry in Vietnam and policy changes for global integration. We find that trade liberalization is a very important policy change that has generally positive impacts and generates strong reactions in the seafood processing industry. Exchange rate depreciation is also an important factor and receives strong responsiveness as most of firms’ intermediate inputs are tradable and seafood products are also tradable. Increasing electricity charges that reduce profitability also generate strong reactions. Oil and petrol comprise a small portion of intermediate inputs, hence increasing the oil price does not significantly hinder the industry and does not stimulate very strong reactions. The US anti‐dumping tariff strongly hurts firms’ profitability, not only seafood exporting firms but also non‐exporters.