bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Agglomeration on Mechanical Properties of Porous Zirconia Fabricated by Partial Sintering
Authors: Deng Zhen‐Yan , Yang Jian‐Feng , Beppu Yoshihisa , Ando Motohide , Ohji Tatsuki
Published: July 2009

Porous ZrO2 ceramics were fabricated by compacting a fine ZrO2 powder, followed by pressureless sintering. Two unidirectional pressures of 30 and 75 MPa were used to prepare the green compacts. The strength and the fracture toughness of porous ZrO2 specimens sintered from the compacts prepared by 75 MPa were substantially higher than those by 30 MPa, especially for the specimens with low porosity. However, the corresponding Young's moduli were identical. This caused the strain to failure of these porous bodies to increase significantly with increasing compaction pressure. Microstructural analyses showed that a number of voids and small flaws existed in the green compacts prepared by the lower pressure, due to the agglomeration of fine ZrO2 grains. It was revealed that the ZrO2 agglomeration resulted in a localized nonuniform shrinkage and degraded the mechanical properties of porous ZrO2 ceramics.
Thermal Shock Resistance of Sintered Alumina/Silicon Carbide Nanocomposites Evaluated by Indentation Techniques
Authors: Maensiri Santi , Roberts Steve G.
Published: July 2009

The thermal shock resistance of sintered Al2O3/1, 2.5, and 5 vol% SiC nanocomposites was studied using two indentation techniques. In the first technique, “indentation thermal shock” measurements were made of the extension of median/radial cracks around Vickers indentations after quenching from various temperatures (up to 480°C) into a bath of boiling water. This technique allowed a critical thermal shock temperature, ΔTCInd, to be quantitatively evaluated. In the second technique, “indentation fatigue” tests were conducted on the thermally shocked specimens; repeated indentations were made at the same site, and the number of load cycles needed to initiate lateral fracture was measured. The results showed that nanocomposites with an addition of SiC nanophase as low as 1 vol% had a thermal shock resistance superior to that of pure Al2O3.
Fabrication of Arsenic Sulfide Optical Fiber with Low Hydrogen Impurities
Authors: Nguyen Vinh Q. , Sanghera Jas S. , Cole Brian , Pureza Pablo , Kung Frederic H. , Aggarwal Ishwar D.
Published: July 2009

Arsenic sulfide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of tellurium tetrachloride (TeCl4) to the glass. During melting, the chlorine from TeCl4 reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to produce optical fibers with significantly reduced loss due to hydrogen sulfide impurity content (1.5 dB/m).
Relationship between Transformation Temperature and Time‐Temperature‐Transformation Curves of Tetragonal‐to‐Monoclinic Martensitic Transformation in Zirconia‐Yttria System
Authors: Tsubakino Harushige , Matsuura Natsuki
Published: July 2009

The tetragonal → monoclinic (t→m) martensitic phase transformation in ZrO2–0.5–4 mol% Y2O3 proceeds during isothermal aging at various temperatures from 350 to 800 K; i.e., the transformation increases sigmoidally with aging time. The time‐temperature‐transformation (T‐ T‐ T) curves show a typical C shape, with very high rate for lower Y2O3‐content specimens, and the rate decreases with higher Y2O3 content. The transformation temperature (Ms) of the t→m transformation obtained from dilatation curves during the cooling stage coincides well with C curves above the nose temperature. The t→m transformation should occur isothermally, as suggested by a nucleation and growth mode.
Lead Hafnate (PbHfO3) Perovskite Powders Synthesized by the Oxidant Peroxo Method
Authors: Camargo Emerson R. , Kakihana Masato
Published: July 2009

Perovskite lead hafnate (PbHfO3, PH) nanoparticles that were free from halides and organics were synthesized via the oxidant peroxo method. Stoichiometric amounts of hafnium nitrate (HfO(NO3)2) and lead nitrate (PbHfO3) were dissolved in a diluted hydrogen peroxide (H2O2) aqueous solution, which was slowly added to a solution of H2O2 and ammonia (NH3) (pH 11). The lead–hafnium precipitate obtained was filtered and washed, to eliminate all nitrate ions. The precipitate was dried, ground, and calcined at temperatures of 400°–900°C. A tetragonal intermediate phase was identified using X‐ray diffractometry and Raman spectroscopy during the calcination process, followed by the crystallization of the orthorhombic PH phase at ∼700°C.
Current‐Voltage Characteristics across (0001) Twist Boundaries in Zinc Oxide Bicrystals
Authors: Sato Yukio , Oba Fumiyasu , Yamamoto Takahisa , Ikuhara Yuichi , Sakuma Taketo
Published: July 2009

Current‐voltage (I–V) characteristics across (0001) twist boundaries with various misorientation angles were investigated in undoped ZnO bicrystals fabricated by a hot‐joining technique. It was confirmed by high‐resolution transmission electron microscopy that the boundaries were perfectly joined without intergranular phase. None of the bicrystals prepared in this study exhibited nonlinear I–V characteristics irrespective of coherency at the boundaries. Therefore, grain‐boundary atomic configuration had no relation to the formation of double Schottky barriers at the (0001) twist boundaries in ZnO.
From CT Scan to Ceramic Bone Graft
Authors: Darsell Jens , Bose Susmita , Hosick Howard L. , Bandyopadhyay Amit
Published: July 2009

An indirect fused deposition process was used to fabricate controlled‐porosity alumina bone grafts using a computer‐aided‐design file created from computed tomography (CT) scans of a horse's short pastern bone. Structures with both uniform and gradient porosity were fabricated to show the effectiveness of this process for the fabrication of custom orthopedic implants. Cytotoxicity and cell proliferation studies were conducted with different cell lines to show that these bone grafts are biocompatible. Uniaxial compression tests were also conducted to understand the influence of porosity on the mechanical properties of these structures.
Fabrication and Evaluation of Porous Piezoelectric Ceramics and Porosity–Graded Piezoelectric Actuators
Authors: Li Jing‐Feng , Takagi Kenta , Ono Masaru , Pan Wei , Watanabe Ryuzo , Almajid Abdulhakim , Taya Minoru
Published: July 2009

Porous ceramics of lead zirconate titanate (PZT) were prepared by sintering powder compacts consisting of PZT and stearic acid powders in an air atmosphere; stearic acid was added as a pore‐forming agent (PFA). The dielectric, elastic and piezoelectric properties of uniformly porous PZT ceramics were investigated as a function of the porosity volume fraction. Furthermore, a beam‐shaped PZT actuator sample with a graded porosity content across its thickness was fabricated by sintering PFA‐graded powder compacts. The electric‐field‐induced bending displacement characteristics of the actuator samples were measured by using strain gauges and were found to be in good agreement with the theoretical predication based on a classical lamination theory.
Effect of 2‐Phosphonobutane‐1,2,4‐tricarboxylic Acid Adsorption on the Stability and Rheological Properties of Aqueous Nanosized 3‐mol%‐Yttria‐Stabilized Tetragonal‐Zirconia Polycrystal Suspensions
Authors: Liu Yangqiao , Gao Lian
Published: July 2009

2‐phosphonobutane‐1,2,4‐tricarboxylic acid (PBTCA) was evaluated as a dispersant for nanosized 3‐mol%‐Y2O3‐stabilized tetragonal‐ZrO2 polycrystal (3Y‐TZP) suspensions. The adsorption of PBTCA was characterized using the decolorization method of ferric 5‐nitrosalicylate complexes. Maximum adsorption of the dispersant on the 3Y‐TZP powder was found to occur at pH 3.0. At pH >3.0, the adsorbed amount decreased with increased pH. Semiquantitative analysis using auger electron spectroscopy showed that PBTCA adsorbed irreversibly on the powder. The surface charge of the powder was evaluated by measuring the zeta‐potential in dilute powder suspensions. The suspension was most effectively stabilized at high pH by the high charge induced by the adsorption of PBTCA. Rheological properties of the suspension were evaluated as a function of dispersant amount and solids loading. The optimum amount of dispersant increased with increased solids loading for solids loading >20 vol%. A stable suspension of 35 nm 3Y‐TZP particles with a solids loading as high as 32 vol% was obtained using PBTCA as dispersant, in contrast to 28 vol% when using ammonium polyacrylate (NH4PAA). Theoretical calculations of the interaction between 3Y‐TZP particles showed that the stabilization of the suspensions was attributed to a combination of the electrostatic repulsion and a steric barrier caused by the adsorbed PBTCA. Induced coupling plasma analysis showed that PBTCA could be completely burned out during sintering, which confirmed its suitability as a dispersant for 3Y‐TZP.
Electronic Structure and Bulk Properties of β‐SiAlONs
Authors: Benco L'ubomír , Hafner Jürgen , Lenčéš Zoltán , Šajgalík Pavol
Published: July 2009

A series of β‐SiAlONs with the composition Si6–zAlzOzN8–z (z= 0.5–4) is prepared by hot isostatic pressing. Evaluated bulk moduli are compared with those calculated using the first‐principles method. Theoretical values are derived from the fit of the energy versus volume dependence. In total‐energy calculations full relaxation of all atomic positions within a supercell is performed. Both experimental and theoretical bulk moduli compare reasonably well and show the decrease in value from ∼240 GPa (z= 0) to ∼170 GPa (z= 4). For the O/N substitutions no preferential occupation of the lattice N sites is observed. Both Al/Si and O/N substitutions cause the local expansion of the structure. In the relaxed structures a sphere of decreased interatomic distances surrounds each substitution site, thus compensating for effect of the local expansion. The increasing Al–O/Si–N substitution rate causes a smooth change of the shape and position of the energy bands. The band gap between occupied and unoccupied states is getting narrower, thus decreasing the isolating properties of the material.
Structure Se nsitivity of Photochemical Oxidation and Reduction Reactions on SrTiO3 Surfaces
Authors: Giocondi Jennifer L. , Rohrer Gregory S.
Published: July 2009

The photochemical reduction of Ag+ and oxidation of Pb2+ from aqueous solution by SrTiO3 leave insoluble reaction products (silver and PbO2, respectively) on the surface. Microscopic analysis has been used to relate the rates of these two reactions to the structure and orientation of SrTiO3 surfaces. The nonpolar (100) surface is the most reactive for silver reduction and the composition of the termination layer does not influence this reaction. On the polar (111) surface, the reduction and oxidation reactions occur on terraces with different terminations and opposite charges; this leads to a nonuniform distribution of reaction products. The polar (110) surface is the least reactive, and the majority of the reaction products are observed at steps along <100> directions where the more reactive {100} surfaces are exposed. The distribution of oxidation products found on (110) terraces is also influenced by the composition and charge of the surface termination. The results show that the photochemical reactivity of SrTiO3 is anisotropic and that, on polar surfaces, dipolar fields arising from charged surface domains influence the transport of photogenerated charge carriers and promote spatially selective oxidation and reduction reactions.
Transmission Electron Microscopy Investigation of Pt/Ba0.7Sr0.3TiO3/Pt Capacitors with Different Annealing Processes
Authors: Qin Yue‐Ling , Jia Chun‐Lin , Liedtke Ralf , Waser Rainer , Urban Knut
Published: July 2009

The effects of postannealing in oxygen ambient and forming gas atmosphere (FGA) on the microstructure and chemistry of Pt/Ba0.7Sr0.3TiO3 (BST)/Pt capacitors prepared by chemical solution deposition have been investigated by means of transmission electron microscopy. The as‐deposited film layers of the Pt/BST/Pt capacitors show a columnar structure. The postannealing in O2 leads to a smoothness of the top film‐electrode interface. The additional FGA treatment applied to the postannealing capacitors introduces disordered or amorphous regions at both top and bottom interfaces. In these regions, deviation in composition from the stoichiometry occurs with a higher Ti/(Ba + Sr) ratio. These amorphous regions are believed to be responsible for the increase of the leakage current obtained in the FGA‐treated capacitors. The thickness of this amorphous interfacial layer can be reduced significantly by a recovery annealing process in air at low temperatures.
Porous Silica Matrix Obtained from Pyrex Glass by Hydrothermal Treatment: Characterization and Nature of the Porosity
Authors: Sigoli Fernando Aparecido , Feliciano Sérgio , Giotto Marcus Vinicius , Davolos Marian Rosaly , Júnior Miguel Jafelicci
Published: July 2009

A novel porous silica matrix has been prepared from Pyrex glass, using hydrothermal treatment under saturated‐steam condition. This process makes it possible to obtain, in one step, a silica support formed of a homogeneously distributed and interconnected macropore microstructure. The new matrix contains silanol groups that can be used in reactions of surface modification to provide a hybrid material and a selective macrofiltration membrane, and also it can improve chemical inertness. The porous matrix is noncrystalline as obtained and, after thermal treatment at temperatures higher than 950°C, exhibits an X‐ray pattern characteristic of α‐cristobalite and low volume contraction. The present samples were characterized by scanning electron microscopy, mercury intrusion porosimetry, nitrogen adsorption‐desorption isotherms, infrared spectroscopy, X‐ray powder diffractometry, atomic absorption, and high‐resolution solid‐state nuclear magnetic resonance. The results present a new way of producing a macroporous silica matrix.
Thermal, Dielectric, and Optical Properties of Neodymium Borosilicate Glasses for Thick Films
Authors: Jung Byung‐Hae , Lee Do‐Kyung , Sohn Sang‐Ho , Kim Hyung‐Sun
Published: July 2009

Because of their thermal, dielectric, and optical properties, new glass compositions and thick‐filmed transparent dielectrics containing neodymium oxide (Nd2O3) were studied as a source of purer images in plasma display panels. In the present study, PbO–B2O3–SiO2 and PbO–B2O3–SiO2–ZnO–Al2O3 were used as starting glass compositions, to which up to 25 wt% of Nd2O3 then was added. Increased amounts of Nd2O3 increased the glass transition temperature and dielectric constant of the bulk glasses and decreased the coefficient of thermal expansion. The fired thick films (around 30 μm) allowed selectively visible light to penetrate and showed deep absorption properties at 585 nm that were related to an extraneous gas from neon discharge.
Centrifugal Casting of Thin‐Walled Ceramic Tubes from Preceramic Polymers
Authors: Melcher Reinhold , Cromme Peter , Scheffler Michael , Greil Peter
Published: July 2009

Thin‐walled (wall thickness, 100–2000 μm) mono‐ and bilayered ceramic tubes in the system Si–O–C–(N) were obtained by centrifugal casting of a polysiloxane/filler suspension. Si and SiC powders were dispersed in polyorganosiloxane/triethoxysilane solutions. After centrifugal casting in a Teflon tube with a rotational speed of 2000 rpm and subsequent cross‐linking at 130°C and 60 rpm, the tubes were pyrolyzed in argon or in nitrogen at 1400–1600°C. Bilayered tubes with controlled variation of porosity were obtained by overcasting the monolayer green tubes with a modified slurry composition.
Damage Behavior in Ceramic Plasma‐Coated and Uncoated Glass with Steel‐Ball Impact
Authors: Suh Chang‐Min , Lee Moon‐Hwan , Hwang Byung‐Won , Kim Sung‐Ho
Published: July 2009

A ceramic plasma‐coating method that reduces damage from particle impact in a ceramic material is suggested. A steel‐ball impact test was performed to investigate and compare the damage behavior of uncoated and ceramic‐coated glass. Cone and lateral crack lengths were compared and damage volume analyzed and compared for different steel‐ball diameters and types of coating materials, Al2O3‐TiO2, Al2O3, and Cr2O3. Damage resistance of the coating and Al2O3‐TiO2 was found to be best because of its mechanical properties and microstructure.
Effect of Bonding Pressure on Silicon Nitride Joining Using a Nickel‐Chromium‐Boron Metal Filler
Authors: Liang Yanan N. , Osendi Maria Isabel , Miranzo Pilar
Published: July 2009

Mechanical pressure exerts a noticeable effect on the reaction that takes place at the interfacial region of Si3N4/Ni‐Cr‐B/Si3N4 joints. In fact, the mechanical pressure affects the thickness of the reaction layer: for lower pressures, a large interfacial reaction layer and a profusion of cracks are observed, whereas, for higher pressures, the extent of the reaction layer is limited, and no cracks are detected. The results show that joint strength increases monotonically with applied pressure.
Factors Affecting the Preparation of Sr2Fe2−xMoxO6
Authors: Fang Tsang‐Tse , Ko Tsun‐Fa
Published: July 2009

Samples of Sr2Fe2−xMoxO6were prepared by solid‐state reaction in air and 5%H2–95%N2. X‐ray diffractometry was used to identify the phases and evaluate the lattice parameters. It is found that molybdenum ions can dissolve in the SrFeO3 even if the sample is heated in air but the solubility is limited. The solubility can be enhanced by heating the sample in low oxygen partial pressure, which is attributed to the larger ionic radii of Fe3+ and Mo5+ than that of Fe4+. The degradation of Sr2Fe2−xMoxO6in water and air is also reported.
Additive‐Enhanced Redispersion of Ceramic Agglomerates
Authors: Uhland Scott A. , Cima Michael J. , Sachs Emanuel M.
Published: July 2009

Deagglomeration of ceramic powders is usually accomplished by immersion of powders in a surfactant‐containing liquid vehicle, followed by milling. We seek alternative mechanisms to the classical milling approach by generating a chemical pressure to break up the agglomerate. This study explores the enhanced redispersion of TiO2 ceramic compacts that contain a nonionic water‐soluble polymer, poly(ethylene glycol) (PEG). PEG forms a polymer solution within the agglomerated structure during redispersion. The resulting osmotic pressure gradient forces water into the porous structure and creates a tensile stress on the particle network with magnitudes as high as 0.6 MPa. Thus, the principle to achieving redispersion is to develop osmotic pressures that exceed the cohesive strength of the agglomerated structure. A critical PEG concentration of 2.0 vol% PEG 400 with respect to titania has been determined, below which redispersion is minimal.
Proton Conductivity in Zr4+‐Ion‐Doped P2O5–SiO2 Porous Glasses
Authors: Nogami Masayuki , Goto Yoichi , Kasuga Toshihiro
Published: July 2009

The effect of zirconium ions on glass structure and proton conductivity was investigated for sol‐gel‐derived P2O5–SiO2 glasses. Porous glasses were prepared through hydrolysis of PO(OCH3)3, Zr(OC4H9)4, and Si(OC2H5)4. Chemical bonding of the P5+ ions was characterized using 31P‐NMR spectra. The phosphorous ions, occurring as PO(OH)3 in the ZrO2‐free glass, were polymerized with one or two bridging oxygen ions per PO4 unit with increased ZrO2 content. The chemical stability of these glasses was increased significantly on the addition of ZrO2, but the conductivity gradually decreased from 26 to 12 mS/cm at room temperature for 10P2O5·7ZrO2·83SiO2 glass. A fuel cell was constructed using 10P2O5·5ZrO2·85SiO2 glass as the electrolyte; a power of ∼4.5 mW/cm2 was attained.
Photocatalytic Silver Recovery Using ZnO Nanopowders Synthesized by Modified Glycine‐Nitrate Process
Authors: Park Sung , Lee Dong‐Woo , Lee Jae‐Chun , Lee Ju‐Hyeon
Published: July 2009

Zinc oxide (ZnO) powders were synthesized by the modified glycine‐nitrate process (MGNP) with various oxidants and fuels. Single‐phase ZnO powders were easily obtained regardless of oxidants and fuels. The particle size and shape of ZnO powders were dependent on the types of fuels. The ZnO powder synthesized using Zn(OH)2 and glycine as an oxidant and a fuel, at a fuel/oxidant ratio of 0.8, showed the best powder characteristics, such as an average grain size of 30 nm and the specific surface area of 120 m2/g. The removal of silver ions from the waste‐development solution was tried to confirm photocatalytic activities of the synthesized ZnO powder. The silver ions were completely removed within 15 min. This silver recovery rate is three times higher than that of commercial state‐of‐the‐art TiO2. The photoluminescence (PL) measurement also showed the PL intensity at ultraviolet (UV) of the synthesized ZnO powder is almost three times higher than that of commercial state‐of‐the‐art TiO2. The synthesized ZnO nanopowder absorbed more UV than any other powders, including commercial state‐of‐the‐art TiO2 and ZnO powders. This means the high UV absorption efficiency leads to the generation of more electrons that are involved in the reduction of silver ions.
Field Emission Characteristics of Amorphous Diamond
Authors: Kan Ming‐Chi , Huang Jow‐Lay , Sung James , Lii Ding‐Fwu , Chen Kuei‐Hsien
Published: July 2009

Amorphous diamond is diamond‐like carbon (DLC) that contains no other impurities. It can be conveniently deposited by bombarding a substrate with a cathodic arc. The arc contains a flux of ionized carbon atoms that are driven by a negative bias. In this research, this bias is set at 20 V. Various forms of amorphous diamond were deposited on silicon substrate of n‐type (100) by varying the arc current set at 30, 50, 80, and 100 A. The sp3/(sp3+ sp2) ratios of these deposited coatings were measured by electron spectroscopy for chemical analysis and Raman spectroscopy, and the asperity height these films were imaged by an atomic force microscope. It was found that the sp3/(sp3+ sp2) ratio peaked at a value of about 50% when the current was set at 80 A. The average roughness increased linearly with the increasing current from ∼0.5 nm at 30 A to about 1.1 nm at 100 A. The maximum asperity height was approximately 10 times that of the above average roughness figures in all cases. The minimum effective work function (Φe) calculated by a Fowler–Nordheim plot was about 0.063 14 eV. By controlling the asperity height of amorphous diamond, high‐emitting efficiencies could be achieved with good reproducibility.
Texture Development in Modified Lead Titanate Thin Films Obtained by Chemical Solution Deposition on Silicon‐Based Substrates
Authors: Ricote Jesús , Poyato Rosalía , Algueró Miguel , Pardo Lorena , Calzada M. Lourdes , Chateigner Daniel
Published: July 2009

An advanced method of X‐ray diffractometry analysis, the quantitative texture analysis, is used in this work to study the preferential orientations of ferroelectric lanthanum‐modified lead titanate thin films, to establish the factors affecting their development. The new, more reliable, texture data obtained allows us to discuss previous models of texture development in chemical‐solution‐deposited films. The results show that a fiber type, mixed <100>,<001> preferential orientation, is obtained when high heating rates are used during crystallization. The degree of texture of these films decreases when successive layers are deposited before a simultaneous crystallization of the ensemble is conducted. This undesirable effect is avoided through layer‐by‐layer crystallization, because of the preferential nucleation of <100>,<001> crystals at the interface between layers. The use of a titanium layer on the platinized silicon‐based substrate leads to the development of an additional fiber <111> texture component. In this case, the layer‐by‐layer crystallization process cannot avoid the loss of the degree of orientation (texture index) with the increase of film thickness. This is mainly caused by the appearance of interlayer porosity, which disrupts the growth of <111>‐oriented grains into upper layers.
Yttrium Silicate Powders Produced by the Sol–Gel Method, Structural and Thermal Characterization
Authors: Boyer Damien , Derby Brian
Published: July 2009

Yttrium silicate (Y2SiO5) powders of high purity have been synthesized using the sol–gel method. Alkoxide precursors were used with commercial tetraethyl orthosilicate as the silica source and yttrium propoxide synthesized from YCl3. Powders calcined from the xerogel showed submicrometer crystal sizes. These powders were sintered at temperatures <1300°C and are suitable for coating applications such as a thermal barrier system for SiC/SiC composites.
Spark Plasma Sintering of Nano‐Sized TiN Prepared from TiO2 by Controlled Hydrolysis of TiCl4 and Ti(O‐i‐C3H7)4 Solution
Authors: Kawano Shuichi , Takahashi Junichi , Shimada Shiro
Published: July 2009

Nano‐sized TiO2 powders were prepared by controlled hydrolysis of TiCl4 and Ti(O‐i‐C3H7)4 solutions and nitrided in flowing NH3 gas at 700°–1000°C to form TiN. Nano‐sized TiN was densified by spark plasma sintering at 1300°–1600°C to produce TiN ceramics with a relative density of 98% at 1600°C. The microstructure of the etched ceramic surface was observed by SEM, which revealed the formation of uniformly sized 1–2 μm grains in the TiCl4‐derived product and 10–20 μm in the Ti(O‐i‐C3H7)4‐derived TiN. The electric resisitivity and Vickers micro‐hardness of the TiN ceramics was also measured.
Application of a Tough Surface Layer to a Fiber‐Bonded Composite
Authors: Kim Yeongseok , Kagawa Yutaka , Zhu Shijie
Published: July 2009

The feasibility of creating “tough surface material” using oxide‐fiber‐reinforced oxide matrix ceramics was studied. Al2O3 fiber/(ZrO2, Al2O3) matrix composite was used as the surface material of a Si–Ti–C–O‐fiber‐bonded composite. The sintering of the matrix (ZrO2 and Al2O3) of the surface composite layer (SCL) and its bonding to the fiber‐bonded composite (FBC) were done simultaneously by vacuum hot pressing. A spherical indentation test demonstrated the advantage of the SCL in reducing the damage of the base FBC from an indenter, because the high fracture resistance of the surface composite layer could reduce the stress concentration by the cumulative microfracture process.
Sol‐Gel Alumina Coating for Improved Cyclic Oxidation Resistance of Silicon Nitride
Authors: Tsarenko Irina , Park Sang , Du Honghua , Lee Woo Y.
Published: July 2009

A 25 nm thick α‐alumina layer was deposited on a turbine‐grade silicon nitride by sol‐gel dip coating and subsequent heat treatment in air at 1200°C. This layer had a nanometer grain structure. Silicon nitride protected by this thin layer showed a significant improvement in oxidation resistance over its uncoated counterpart after 200 cyclic exposures in air at 1250°C. The oxide layer grown on the coated silicon nitride also exhibited superior surface morphology, compared with the uncoated silicon nitride.
Positronium Annihilation Study of Porosity in Silica Xerogels Prepared by a Sol–Gel Process
Authors: Wakabayashi Yuki , Ito Kenji , Li Hong‐Ling , Ujihira Yusuke , Kamitani Kazuya , Inoue Hiroyuki , Makishima Akio
Published: July 2009

Nano‐ and mesopores of bulk silica xerogels were studied by means of positron annihilation lifetime measurement as well as nitrogen physisorption. Effects of an alkaline catalyst concentration in the sol–gel process on the pore sizes and specific surface area were investigated. The pore size was estimated from the ortho‐positronium lifetime. Remarkable structural changes were found around a relative alkaline concentration of 10−4 (a molar ratio of sodium hydroxide to tetramethyl ortho‐silicate). Above this particular catalyst concentration, the nanopore radius decreased from 0.45 to 0.35 nm, whereas the mesopore radius increased from 1 to 8 nm. The positron annihilation lifetime technique was effective in the evaluation of the nano‐ and mesoscopic structural changes of silica xerogel.
Nanostructured Silicon Oxide–Nickel Oxide Sol–Gel Films with Enhanced Optical Carbon Monoxide Gas Sensitivity
Authors: Martucci Alessandro , Pasquale Mirko , Guglielmi Massimo , Post Mike , Pivin Jean Claude
Published: July 2009

Sol–gel derived silica (SiO2) films doped with nickel oxide (NiO) nanocrystals were fabricated. A bifunctional ligand was used, bearing amine groups capable of coordinating the nickel ions and hydrolysable siloxane groups for anchoring the metal complex moiety to the silicate matrix. Nickel oxide nanocrystals precipitated at 500°C while the film was still porous. The nanocomposite films showed a reversible change in the optical transmittance in the VIS‐NIR range when exposed to carbon monoxide gas. The effects of residual porosity, testing temperature, and carbon monoxide gas concentration on optical transmittance were studied.
Characteristics of prostate cancers found in specimens removed by radical cystoprostatectomy for bladder cancer and their relationship with serum prostate‐specific antigen level
Authors: Nakagawa Tohru , Kanai Yae , Komiyama Motokiyo , Fujimoto Hiroyuki , Kakizoe Tadao
Published: July 2009

Prostate cancer mass screening using serum prostate‐specific antigen (PSA) has been conducted widely in the world. However, little is known about the true prevalence of prostate cancer in the ‘normal’ PSA range (4.0 ng/mL or less). The aim of the present study was to elucidate the clinicopathological features of prostate cancer occurring in men with a wide range of PSA levels. The study comprised 349 male patients who underwent radical cystoprostatectomy for bladder cancer. Patients who had had treatment for known prostate cancer were excluded. Tissue specimens were reviewed microscopically. Ninety‐one patients (26.1%) were found to have prostate cancer, and 68 (74.7%) of these 91 cancers were considered to be clinically significant. Both increasing patient age and PSA level were significantly correlated with an increased incidence of both all and significant prostate cancers. Sixty‐five (21.9%) among 297 patients with PSA < 4.0 ng/mL had prostate cancer, and 45 (69.2%) of the 65 cancers were significant cancers. Eighteen patients had prostate cancers 0.5 mL or more in volume. Among the 18 patients, the PSA level was 4 ng/mL or more in 11, and 3 ng/mL or more in 15. Our study shows that prostate cancer is a common finding in radical cystoprostatectomy specimens excised because of bladder cancers, and a significant proportion of these cancers are clinically significant. PSA still appears to be a useful screening tool for detecting prostate cancers with significant volume. (Cancer Sci 2009; 100: 1880–1884)
Dynamic models allowing for flexibility in complex life histories accurately predict timing of metamorphosis and antipredator strategies of prey
Authors: Higginson Andrew D. , Ruxton Graeme D.
Published: July 2009

1. The development of antipredator defences in the larval stage of animals with complex life cycles is likely to be affected by costs associated with creating and maintaining such defences because of their impact on the timing of maturation or metamorphosis.

2. Various theoretical treatments have suggested that investment in defence should both increase or decrease with increasing resource availability, but a recent model predicts investment in defences should be highest at intermediate resource level and predator density.

3. Previous models of investment in defence and timing of metamorphosis provide a poor match to empirical data. Here we develop a dynamic state‐dependent model of investment in behavioural and morphological defences that enables us to allow flexibility in investment in defences over development, the timing of metamorphosis and the size of the organism at metamorphosis that were absent from previous theory.

4. We show that the inclusion of this flexibility results in different predictions to those of the fixed investment approach used previously, especially when we allow metamorphosis to occur at the optimal time and state for the organism.

5. Under these more flexible conditions, we predict that morphological defences should be insensitive to resource level whilst behavioural defences should either increase or decrease with increasing resources depending on the predation risk and the magnitude of the fitness benefits of large size at metamorphosis.

6. Our work provides a formal framework in which we might progress in the study of how the use of antipredator defences is affected by their costs. Most of the predictions of our model in are in good accord with empirical results, and can be understood in terms of the underlying biological assumptions. The reasons why simpler models failed to match empirical observations can be explained, and our predictions that are a poor match help to target the circumstances which warrant future study.
Predicting the distribution of Sasquatch in western North America: anything goes with ecological niche modelling
Authors: Lozier J. D. , Aniello P. , Hickerson M. J.
Published: July 2009

The availability of user‐friendly software and publicly available biodiversity databases has led to a rapid increase in the use of ecological niche modelling to predict species distributions. A potential source of error in publicly available data that may affect the accuracy of ecological niche models (ENMs), and one that is difficult to correct for, is incorrect (or incomplete) taxonomy. Here we remind researchers of the need for careful evaluation of database records prior to use in modelling, especially when the presence of cryptic species is suspected or many records are based on indirect evidence. To draw attention to this potential problem, we construct ENMs for the North American Sasquatch (i.e. Bigfoot). Specifically, we use a large database of georeferenced putative sightings and footprints for Sasquatch in western North America, demonstrating how convincing environmentally predicted distributions of a taxon’s potential range can be generated from questionable site‐occurrence data. We compare the distribution of Bigfoot with an ENM for the black bear, Ursus americanus, and suggest that many sightings of this cryptozoid may be cases of mistaken identity.
Long‐term changes in soils of second‐growth forest following abandonment from agriculture
Authors: Matlack Glenn R.
Published: July 2009

Aim  The assembly of a forest flora on sites abandoned from agriculture is potentially limited by the physical and chemical suitability of soils. This paper describes the post‐agricultural development of soil in deciduous forest sites to gauge its importance in limiting a second‐growth forest flora.

Location  Northern Delaware and south‐eastern Pennsylvania, USA.

Methods  A chronosequence of 99 second‐growth forest sites was assembled in the Piedmont region. Stand age ranged from 0–20 to > 100 years since canopy closure, as determined from historical aerial photographs. Seventy‐four sites are likely to have experienced cultivation before regeneration of forest. The presence of large rocks or pit‐and‐mound microtopography suggests that the remaining 25 sites were not cultivated, although they were probably used as pasture and/or woodlot. Soil organic content, moisture, pH, and concentrations of extractable potassium, phosphorous, calcium, magnesium and sulphur were measured in samples from each site. Coarse woody debris, size of the largest tree, canopy openness and several microtopographic features were also recorded.

Results  Most soil variables fell into two separate but internally correlated groups: the first group including organic matter, moisture and sulphur; the second including pH, calcium, potassium and magnesium. In formerly cultivated sites, organic matter, moisture and sulphur increased gradually through the chronosequence, approaching values recorded in uncultivated sites at 81–100 years. Calcium, potassium, magnesium and pH declined sharply between the 21–40‐ and 41–60‐year classes – probably an indirect effect related to geographic location and selective abandonment. Phosphorous also declined with time, but the decline was not as clearly defined.

Main conclusions  The progress of soil recovery observed here is faster than rates implied in other studies, possibly because these sites experienced a period as pasture before reversion to forest. Sites appear to have returned to undisturbed‐forest levels as fast as or faster than the predicted accumulation of a forest flora, suggesting that assembly of second‐growth forest communities is not limited by the rate of soil development in this region.
Expression patterns of glial fibrillary acidic protein (GFAP)‐delta in epilepsy‐associated lesional pathologies
Authors: Martinian L. , Boer K. , Middeldorp J. , Hol E. M. , Sisodiya S. M. , Squier W. , Aronica E. , Thom M.
Published: July 2009

Aims: Glial fibrillary acidic protein (GFAP)‐δ is a novel isoform that differs in its C‐terminal sequence from other GFAP isoforms. Previous studies suggest restriction of expression to the subpial layer, subventricular zone and the subgranular zone astrocytes, with an absence in pathological conditions causing reactive gliosis. GFAP‐δ is speculated to have roles in regulation of astrocyte size and motility and a subpopulation of GFAP‐δ‐positive glia may be multipotent stem cells. The aim of this study was to investigate its expression in common causes of lesion‐related refractory epilepsy. Methods: Hippocampal sclerosis (HS), focal cortical dysplasia (FCD) type IIB, cortical tuberous sclerosis (TSC) lesions, gangliogliomas, grey matter heterotopias and hemimegalencephaly from a wide age range of patients using both surgical and post mortem tissue specimens were studied. Results: GFAP‐δ expression was observed in CA4 and CA1 astrocytes in HS with less frequent labelling in the granule cell layer, even where granule cell dispersion was present. No significant labelling was noted in the subiculum in HS cases or in any subfields in non‐HS epilepsy cases. Balloon cells in FCDIIB and hemimegalencephaly, giant cells in TSC and the astrocytic component of gangliogliomas showed immunoreactivity, colocalizing with conventional GFAP. No neuronal expression for GFAP‐δ was seen in any of the pathologies. Quantitative analysis in 10 FCDIIB and five TSC cases revealed greater numbers of GFAP‐δ‐positive balloon cells than conventional GFAP. There was no GFAP‐δ expression within nodular heterotopia. Conclusions: GFAP‐δ expression patterns in HS overall appears to mirror regional reactive gliosis. It is a useful marker for the demonstration of balloon cells in FCD and TSC, which may be relevant to their abnormal size and localization. The lack of GFAP‐δ within heterotopia supports their composition from cells destined for deeper cortical layers.
Thyroidization in renal allografts
Authors: Ito Shinichi , Kobayashi Akimitsu , Tsuchiya Tomohiro , Moriyama Yoji , Kikuchi Mina , Deguchi Takashi , Yamaguchi Yutaka
Published: July 2009

Abstract:  Thyroidization (thyroid‐like appearance) in renal tissue which is made up of a colloid‐like hyaline cast formation of Tamm‐Horsfall glycoprotein (THP) is a common finding in chronic pyelonephritis and obstructive nephropathy. This type of pathological change is sometimes observed in renal allograft specimens. We examined allograft specimens for thyroidization and other pathological findings related to thyroidization to characterize the conditions causing such changes. One‐hundred three patients who underwent renal transplantation between January 2006 and April 2008 at Gifu University Hospital (251 renal allograft biopsy specimens) were enrolled in this study. Sixteen patients had thyroidization (11 mild, 4 moderate, and 1 severe). In four patients, THP reflux on Bowman’s capsule was found, and in three patients interstitial THP deposits were observed. In four patients, tubulointerstitial nephritis was diagnosed. Fifteen of 16 patients were examined for vesicoureteral reflux (VUR) with voiding cystourethrography. Three of 15 patients had VUR. In the past medical histories of the 16 patients with thyroidization, three had low capacity bladders, two had prostate diseases, and six had previous urinary tract infections. In cases of thyroidization with additional findings, including THP reflux into Bowman’s space and interstitial THP deposits, we need to examine the patients for the presence of urinary tract diseases. In cases of thyroidization and tubulointerstitial nephritis urinary tract infections were suspected. Such subclinical urological diseases in the grafts might affect the prognosis of renal function. Therefore, appropriate management of urinary tract diseases is required.
A case of accelerated acute rejection after ABO‐compatible living unrelated kidney transplantation
Authors: Matsuo Nanae , Yamamoto Hiroyasu , Kobayashi Akimitsu , Yamamoto Izumi , Mitome Jun , Maruyama Yukio , Hayakawa Hiroshi , Miyazaki Yoichi , Utsunomiya Yasunori , Hosoya Tatsuo , Yamaguchi Yutaka
Published: July 2009

Abstract:  A 59‐yr‐old Japanese woman with chronic renal failure caused by IgA nephropathy and antineutrophil cytoplasmic antibody (ANCA)‐related glomerulonephritis underwent kidney transplantation from a living unrelated spousal donor. The blood type was compatible, while the human leukocyte antigen (HLA) typing showed a 5/6 locus mismatch. She had become pregnant twice by her donor and had never received blood transfusions. Complement‐dependent cytotoxicity cross‐match, flow cytometry cross‐match (FCXM), and flow panel reactive antibody (PRA) were negative. She initially underwent one week of immunosuppression with mycophenolate mofetil (MMF) and double filtration plasmapheresis (DFPP) immediately before transplantation to reduce the risk of antibody‐mediated rejection. Induction therapy consisted of MMF, tacrolimus (TAC), methylprednisolone (MP), and basiliximab. The allograft function was excellent immediately after the operation. However, the urine output and platelet count declined rapidly on post‐operative day (POD) 3, while the serum creatinine (sCr) and lactate dehydrogenase levels rose gradually. Subsequently, we could not detect the diastolic arterial flow on Doppler sonography. We diagnosed accelerated acute rejection and treated her with plasma exchange (PEX), intravenous MP pulse therapy, and rituximab. The first episode biopsy on POD 7 revealed acute vascular rejection and acute antibody‐mediated rejection (Banff score AMR II). Her urinary excretion increased beginning on POD 13, while the sCr level decreased gradually and reached 0.9 mg/dL on POD 22. In our retrospective analysis, the LAB screen detected donor‐specific antibody (DSA). This case suggested that, for successful kidney transplantation in highly sensitized recipients, such as husband‐to‐wife spousal kidney transplantation with a history of pregnancy, we should keep the risk of AMR in mind, even if the sensitive antibody detection tests are negative.
Two cases of ANCA‐associated vasculitis in post‐transplant kidney: relapse and de novo
Authors: Tabata Hidehiro , Honda Kazuho , Moriyama Takahito , Itabashi Mitsuyo , Taneda Sekiko , Takei Takashi , Tanabe Kazunari , Teraoka Satoshi , Yamaguchi Yutaka , Oda Hideaki , Nitta Kosaku
Published: July 2009

Abstract:  Two cases of anti‐neutrophil cytoplasmic antibody (ANCA) associated vasculitis (ANCA‐V) occurred in the transplanted kidney were reported. Case 1 was a 57 yr‐old female whose original disease was MPO‐ANCA‐V. A relapse of necrotizing crescentic glomerulonephritis occurred one year after transplantation with positive serum reaction for MPO‐ANCA. In spite of several immunosuppressive treatments, the disease progressed and she returned to hemodialysis treatment three yr and seven months after transplantation. Case 2 was a 34 yr‐old female whose original disease was IgA nephropathy. She had a stable clinical condition during 13 yr after transplantation; however, de novo onset of necrotizing crescentic glomerulonephritis occurred at 14 yr 10 months after transplantation with positive serum reaction for MPO‐ANCA. She returned to hemodialysis treatment five yr after the onset of ANCA‐V. Urinary abnormities such as microhematuria and proteinuria were useful diagnostic findings but the titers of serum MPO‐ANCA were relatively low in both patients. Concerning the treatment, steroid pulse therapy was effective in some extents but the disease progressed to graft failure in both cases. ANCA‐V is a severe glomerulonephritis which can occur in kidney allograft in the manner of relapse and de novo. Detection of urinary abnormalities and positive serum ANCA combined with histological confirmation of necrotizing crescentic glomerulonephritis and/or vasculitis is required for early diagnosis and effective treatment of ANCA‐V in renal transplant patients.
A long‐term prevention of diabetic nephropathy in a patient with type 1 diabetes after simultaneous pancreas and kidney transplantation
Authors: Nyumura Izumi , Honda Kazuho , Babazono Tetsuya , Taneda Sekiko , Horita Shigeru , Teraoka Satoshi , Yamaguchi Yutaka , Iwamoto Yasuhiko , Oda Hideaki
Published: July 2009

Abstract:  We report a case of type 1 diabetes mellitus who was successfully treated with simultaneous pancreas and kidney (SPK) transplantation and both grafts survived for 16 yr. A 30‐yr‐old woman underwent SPK transplantation from a non‐heart‐beating donor in January 1992. She was treated with combined immunosuppressive therapy consisting of cyclosporine, azathioprine, methylprednisolone, and anti‐lymphocyte globulin. Allograft kidney biopsy was performed 10 yr after transplantation to determine the cause of proteinuria, which revealed no recurrence of diabetic nephropathy, suggesting that long‐term normalization of glycemic control achieved by successful pancreas transplantation can prevent recurrence of diabetic nephropathy in the kidney allograft.
Histopathologic evaluation of living kidney donor candidates by pre‐operative kidney biopsy
Authors: Okamoto Masahiko , Sakai Kazuki , Suzuki Tomoyuki , Nobori Shuji , Ushigome Hidetaka , Sakamoto Seisuke , Urasaki Koji , Mori Yasukiyo , Akioka Kiyokazu , Daimon Shoichiro , Yoshimura Norio
Published: July 2009

Abstract:  A lack of deceased kidney donors in Japan has led to dependence on living donors in as many as 80% of cases. At the same time, indications for living‐donor kidney donation have been expanding in terms of donor medical status as well as HLA matching and ABO compatibility, thus emphasizing the donor shortage. To facilitate final medical decision‐making for living kidney donation, we attempted kidney biopsy in six donor candidates who had problems such as mild diabetes and slight proteinuria. The biopsy specimens showed various degrees of tissue injury ranging from partial glomerular sclerosis to arteriole hyalinization. On the basis of the biopsy findings, kidney donation was subsequently performed in three of the six cases with full informed consent, and not done in the remaining three cases. Longer‐term studies will be needed to clarify the outcome in both the donors and recipients in these cases.