bluuebunny/crossref_metadata_2025 huggingface dataset:
Additive Effects on Si3N4 Oxidation/Volatilization in Water Vapor
Authors: Opila Elizabeth J. , Robinson R. Craig , Fox Dennis S. , Wenglarz Richard A. , Ferber Mattison K.
Published: July 2009

Two commercially available additive‐containing silicon nitride materials were exposed in four environments which ranged in severity from dry oxygen at 1 atm pressure, and low gas velocity, to an actual turbine engine. Oxidation and volatilization kinetics were monitored at temperatures ranging from 1066° to 1400°C. The main purpose of this paper is to examine the surface oxide morphology resulting from the exposures. It was found that the material surface was enriched in rare‐earth silicate phases in combustion environments when compared with the oxides formed on materials exposed in dry oxygen. However, the in situ formation of rare‐earth disilicate phases offered little additional protection from the volatilization of silica observed in combustion environments. It was concluded that externally applied environmental barrier coatings are needed to protect additive‐containing silicon nitride materials from volatilization reactions in combustion environments.
High‐Temperature Stability of SiC‐Based Composites in High‐Water‐Vapor‐Pressure Environments
Authors: More Karren L. , Tortorelli Peter F. , Walker Larry R. , Miriyala Naren , Price Jeffrey R. , van Roode Mark
Published: July 2009

Microstructural characterization of boron‐containing SiC‐reinforced SiC composites exposed at high temperature in high‐water‐vapor‐pressure environments was used to determine surface recession rates and to understand the controlling degradation processes under these conditions. Results showed that composite degradation was controlled by a series of reactions involving the formation of silica, boria, borosilicate glass, and gaseous products. Comparison of results (from characterization of composites exposed at 1200°C and 1.5 atm of H2O in a laboratory furnace and in the combustion zone of a gas turbine) showed that these reactions were common to both exposure conditions and, consequently, there was little effect of gas velocity on degradation rates of boron‐containing SiC/SiC composite materials.
Upper Temperature Limit of Environmental Barrier Coatings Based on Mullite and BSAS
Authors: Lee Kang N. , Fox Dennis S. , Eldridge Jeffrey I. , Zhu Dongming , Robinson Raymond C. , Bansal Narottam P. , Miller Robert A.
Published: July 2009

Current state‐of‐the‐art environmental barrier coatings (EBCs) for Si‐based ceramics consist of three layers: a silicon bond coat, an intermediate mullite (3Al2O3·2SiO2) or mullite + BSAS ((1−x)BaO·xSrO·Al2O3·2SiO2, 0 ≤x≤ 1) layer, and a BSAS top coat. Areas of concern for long‐term durability are environmental durability, chemical compatibility, volatility, phase stability, and thermal conductivity. Variants of this family of EBC were applied onto monolithic SiC and melt‐infiltrated SiC/SiC composites. Reaction between BSAS and silica results in a low‐melting (∼1300°C) glass, which can cause the spallation of the EBC. At temperatures greater than ∼1400°C BSAS suffers significant recession via volatilization in water‐vapor‐containing atmospheres. Both reactions can be EBC life‐limiting factors. BSAS undergoes a very sluggish phase transformation (hexagonal celsian to monoclinic celsian), the implications of which are not fully understood at this point. Initial rapid increase in thermal conductivity at temperatures as low as 1300°C indicates the sintering of EBC.
Microwave Sintering of Alumina at 2.45 GHz
Authors: Brosnan Kristen H. , Messing Gary L. , Agrawal Dinesh K.
Published: July 2009

The sintering kinetics and microstructural evolution of alumina tubes (∼17 mm length, ∼9 mm inner diameter, and ∼11 mm outer diameter) were studied by conventional and microwave heating at 2.45 GHz. Temperature during microwave heating was measured with an infrared pyrometer and was calibrated to ±10°C. With no hold at sintering temperature, microwave‐sintered samples reached 95% density at 1350°C versus 1600°C for conventionally heated samples. The activation energy for microwave sintering was 85 ± 10 kJ/mol, whereas the activation energy for conventionally sintered samples was 520 ± 14 kJ/mol. Despite the difference in temperature, grains grew from ∼1.0 μm at 86% density to ∼2.6 μm at 98% density for both conventionally sintered and microwave‐sintered samples. The grain size/density trajectory was independent of the heating source. It is concluded that the enhanced densification with microwave heating is not a consequence of fast‐firing and therefore is not a result in the change in the relative rates of surface and grain boundary diffusion in the presence of microwave energy.
Synthesis of Nanocrystalline α‐Al2O3 Powders from Nanometric Ammonium Aluminum Carbonate Hydroxide
Authors: Sun Xudong , Li Jiguang , Zhang Fang , Qin Xiaomei , Xiu Zhimeng , Ru Hongqiang , You Jian
Published: July 2009

Nanometric ammonium aluminum carbonate hydroxide (AACH) with a particle size less than 5 nm was produced from ammonium aluminum sulfate and ammonium hydrocarbonate under an optimized adding condition, and phase transformations of the AACH on heating and the effect of α‐Al2O3 seeding on the transformation kinetics were investigated. The phase transformation sequence of AACH on heating was found to be AACH → amorphous Al2O3→γ‐Al2O3→θ‐Al2O3→α‐Al2O3, where the formation temperatures of θ‐Al2O3 and α‐Al2O3 are 850° and 1050°C, respectively. The phase transformation sequence on heating of the AACH seeded with 5 wt%α‐Al2O3 seed crystals 100 nm in diameter was found to be AACH → amorphous Al2O3→θ‐Al2O3→α‐Al2O3. γ‐Al2O3 was not observed, and the θ‐Al2O3→α‐Al2O3 transformation temperature was reduced to 900°C by the seeding. By calcining the γ‐AlOOH, the AACH, and the seeded AACH at their lowest temperatures to transform completely to α‐Al2O3 (i.e., about 1200°, 1100°, and 900°C, respectively), α‐Al2O3 powders have been obtained with mean particle sizes of about 150, 70, and 30 nm, respectively. The α‐Al2O3 powder produced from the seeded AACH has the highest sintering reactivity. After sintering at 1400°C for 2 h, relative densities of the powder compacts of α‐Al2O3 obtained by calcining γ‐AlOOH, AACH, and the seeded AACH are 74.3%, 95.0%, and 98.5%, respectively.
Low‐Thermal‐Expansion Properties of Sodium‐ and Lithium‐Substituted Cubic Cesium Leucite Compounds
Authors: Yanase Ikuo , Tamai Sachiko , Kobayashi Hidehiko
Published: July 2009

Cubic cesium leucite‐based compounds, namely cesium leucites, cesium sodium leucites, and cesium lithium leucites, were synthesized using a multistep solid‐state reaction method. The thermal expansion properties, in the temperature range of 298‐1273 K, for the synthesized cubic cesium leucite‐based compounds were examined using high‐temperature powder X‐ray diffractometry data. The thermal expansions of the cubic cesium leucite‐based compounds were found to vary with the chemical composition. For instance, the thermal expansions of Cs0.7Na0.2Al0.9Si2.1O6 and Cs0.7Li0.2Al0.9Si2.1O6 were 0.14% at 1273 K and 0.081% at 1073 K, values lower than those of Cs0.9Al0.9Si2.1O6, which were 0.16% at 1073 K and 0.2% at 1273 K. The results showed that the thermal expansions of the cubic cesium leucite‐based compounds changed with ionic substitution at the Cs+ sites because of ionic size differences between Cs+ and the Na+ or Li+ substitutional ions.
Fabrication of Single‐Crystal α‐Al2O3 Nanorods by Displacement Reactions
Authors: Deng Cheng‐Ji , Yu Peng , Yau Man‐Yan , Ku Chiu‐Shan , Ng Dickon H. L.
Published: July 2009

Nanometer‐sized Al2O3 rods are fabricated by sintering a powder mixture of Al and SiO2. The sintered product is leached in HF–HNO3 solution, followed by rinsing and washing before the nanorods are collected. The yield of the product is about 50 wt%. Transmission electron microscopy reveals that these rods are 1 to 2 μm long and have a diameter of 20 to 100 nm, while electron diffraction confirms that these rods are single crystals of α‐Al2O3. It is observed that these rods have either round or slightly sharp tips, which is different from those having droplet‐like tips that are usually found in products fabricated by catalytic reactions.
Structure of Calcium Silicate Hydrates Formed in Alkaline‐Activated Slag: Influence of the Type of Alkaline Activator
Authors: Fernández‐Jiménez Ana , Puertas Francisca , Sobrados Isabel , Sanz Jesús
Published: July 2009

The influence of the alkaline activator (NaOH, waterglass, or Na2CO3) on the structure of the hydrated calcium silicate formed in alkali‐activated slag (AAS) cement pastes has been investigated by FTIR, 29Si and 27Al magic‐angle scattering nuclear magnetic resonance, and TEM/EDX techniques. In all cases, the main product formed after 7 d of activation, with activators giving an Na2O concentration of 4%, is a semicrystalline calcium silicate hydrate with a dreierkette‐type anion. In these structures, linear finite chains of silicate tetrahedra (Q2 units) are linked to central Ca‐O layers, and tetrahedral aluminum occupies bridging positions in the chains. The main chain length and the amount of aluminum incorporated in the tetrahedral chains depend on the activator used. The detection of Q3 silicon entities in alkaline‐activated slags is discussed in relation to the possible formation of cross‐linked structures that may be responsible for increased flexural and compressive strengths in AAS mortars.
Microstructure Characterization of the (1−x)La2/3TiO3·xLaAlO3 System
Authors: Lee Hwack Joo , Park Hyun Min , Cho Yang Koo , Nahm Sahn
Published: July 2009

Microstructural characterizations on the (1−x)La2/3TiO3·xLaAlO3 (LTLA) system were conducted using transmission electron microscopy. The presence of La2Ti2O7 and La4Ti9O24 phases in pure La2/3TiO3 is confirmed by the electron diffraction pattern. When x= 0.1, the ordering due to the A‐site vacancies could be confirmed by the presence of antiphase boundaries (APBs) and return ½(100) superlattice reflection. As xincreases, the ordering decreases and finally disappears when x= 0.6. The tilting of oxygen octahedra could be demonstrated by the presence of the ferroelastic domains in the matrix and return ½(111) and return ½(110) superlattice reflections in selected area electron diffraction patterns. In pure LaAlO3, only the antiphase tilting of oxygen octahedra is present due to the presence of return ½(111) superlattice reflection. In the LTLA system of x= 0.1, both the antiphase and in‐phase tiltings of the oxygen octahedra are involved; however, in the range of x from 0.3 to 0.9, the antiphase tilting of oxygen octahedra has appeared. The growth of the ferroelastic domains is influenced by the APBs in the matrix.
Cubic‐Formation and Grain‐Growth Mechanisms in Tetragonal Zirconia Polycrystal
Authors: Matsui Koji , Horikoshi Hideharu , Ohmichi Nobukatsu , Ohgai Michiharu , Yoshida Hidehiro , Ikuhara Yuichi
Published: July 2009

The microstructure in Y2O3‐stabilized tetragonal zirconia polycrystal (Y‐TZP) sintered at 1300°–1500°C was examined to clarify the role of Y3+ ions on grain growth and the formation of cubic phase. The grain size and the fraction of the cubic phase in Y‐TZP increased as the sintering temperature increased. Both the fraction of the tetragonal phase and the Y2O3 concentration within the tetragonal phase decreased with increasing fraction of the cubic phase. Scanning transmission electron microscopy (SEM) and X‐ray energy dispersive spectroscopy (EDS) measurements revealed that cubic phase regions in grain interiors in Y‐TZP generated as the sintering temperature increased. High‐resolution electron microscopy and nanoprobe EDS measurements revealed that no amorphous layer or second phase existed along the grain‐boundary faces in Y‐TZP and Y3+ ions segregated at their grain boundaries over a width of ∼10 nm. Taking into account these results, it was clarified that cubic phase regions in grain interiors started to form from grain boundaries and the triple junctions in which Y3+ ions segregated. The cubic‐formation and grain‐growth mechanisms in Y‐TZP can be explained using the grain boundary segregation‐induced phase transformation model and the solute drag effect of Y3+ ions segregating along the grain boundary, respectively.
Multiaxial Deformation Behavior of PZT from Torsion Tests
Authors: Fett Theo , Munz Dietrich , Thun Gerhard
Published: July 2009

Torsion tests were conducted on thin‐walled tubes made of a commercial soft PZT. These tests in combination with literature results from tensile and compression tests allowed determination of the nonsymmetric yield condition for the plastic deformations. Good agreement with the Drucker–Prager criterion was found.
Measurement of Fracture Toughness of Plasma‐Sprayed Al2O3 Coatings Using a Tapered Double Cantilever Beam Method
Authors: Li Chang‐Jiu , Wang Wei‐Ze , He Yong
Published: July 2009

The fracture toughness of plasma‐sprayed Al2O3 coatings in terms of the critical strain energy release rate GIc was measured using a tapered double cantilever beam (TDCB) approach. The fracture surfaces were examined using a scanning electron microscope (SEM). The measurement yielded the mean GIc values from 13 to 27 J/m2 for the sprayed Al2O3 coatings at different spray distances. These values agree well with those obtained by the conventional double cantilever beam approach. The dependence of the observed GIc on spray distance is consistent with that for the lamellar bonding ratio. These results suggest that the TDCB test is a reliable approach for measuring the GIc of thermal‐spray coatings without the crack‐length measurement.
A Simple Direct Casting Route to Ceramic Foams
Authors: Dhara Santanu , Bhargava Parag
Published: July 2009

A simple direct foaming and casting process using ovalbumin‐based aqueous slurries for fabricating ceramic and metal foams is demonstrated. Foaming of aqueous ceramic slurries and the foam microstructure were seen to be a strong function of slurry rheology. Setting of foams with ceramic solids loading above 20 vol% was achieved by addition of acid, which also prevented binder migration. Acid addition resulted in excessive shrinkage, causing cracking of foams with ceramic loading below 20 vol%. Addition of sucrose to the slurries suppressed shrinkage leading to defect‐free foams with porosity exceeding 95%. Overall porosity and foam microstructure could be controlled through ceramic solids loading, ovalbumin–water ratio, foaming time and sucrose amount, and sintering temperature. The ceramic foams fabricated by the process were strong enough to be green machined to different shapes.
Influence of Barium Dissolution on the Electrokinetic Properties of Colloidal BaTiO3 in an Aqueous Medium
Authors: Paik Ungyu , Lee Sangkyu , Hackley Vincent A.
Published: July 2009

Hysteresis in the electrokinetic behavior of colloidal hydrothermal BaTiO3 occurs during sequential acid and base titrations. Ba dissolution during acid titration results in an oxide‐rich surface. When the acid‐treated BaTiO3 is titrated back to pH 10, dissolved Ba is specifically adsorbed and/or precipitated onto the particle surface. The combined effects of dissolution and subsequent adsorption–precipitation results in titration hysteresis. Most of the labile Ba can be removed by multiple acid treatments, which result in a TiO2‐like surface layer composition. Barium dissolution increases with decreasing pH but levels off below pH 4 due to diffusion through the surface oxide layer as predicted previously. A phenomenological model is offered to explain the electrokinetic behavior as a function of pH. It is suggested that inherent BaCO3 contamination is not the primary source of dissolved Ba from hydrothermal BaTiO3 in acidic solution.
Synthesizing and Comparing the Photocatalytic Properties of High Surface Area Rutile and Anatase Titania Nanoparticles
Authors: Sun Jing , Gao Lian , Zhang Qinghong
Published: July 2009

Rutile titania nanocrystalline particles with high specific surface areas were directly prepared by thermal hydrolysis of titanium tetrachloride aqueous solution. The as‐prepared rutile titania powder was characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller surface area analysis, and Fourier transform Raman and IR spectroscopies. Neither anatase nor amorphous titania could be detected in this titania powder by XRD, Raman spectroscopy, and high‐resolution TEM. In the phenol degradation reaction, the rutile titania powder with an initial crystalline size of 7 nm was found to have higher photocatalytic activity than that of anatase titania with the same specific surface area. The rutile titania powders calcined at 300° and 450°C also showed a relatively high photocatalytic property. The high activity of the as‐prepared rutile titania was attributed to the abundance of hydroxy groups in the powder, as was proven by thermogravimetric analysis data, which provided more active sites for the degradation reaction.
Band Gap Modification of Diamond Photonic Crystals by Changing the Volume Fraction of the Dielectric Lattice
Authors: Kanehira Shingo , Kirihara Soshu , Miyamoto Yoshinari , Sakoda Kazuaki , Takeda Mitsuo Wada
Published: July 2009

Photonic crystals with a diamond structure of epoxy lattices in which TiO2‐based ceramic particles are dispersed were fabricated by stereolithography. The periodicity of the lattice was designed to reflect electromagnetic waves in the gigahertz range. The volume fraction (β) of the dielectric lattice medium was modified from 14% to 33% by changing the rod diameter of the lattice. The photonic band gap was observed along Γ‐L 〈111〉, Γ‐X 〈100〉, and Γ‐K 〈110〉 directions and the complete photonic band gap was formed at over β= 20%. The width of the forbidden gap increased gradually when the β increased over 14%, and reached 2.4 GHz at β= 33%. These results agreed with the band calculation using the plane wave expansion method.
Defect Structures of Tin‐Doped Indium Oxide
Authors: Warschkow Oliver , Ellis Donald E. , González Gabriela B. , Mason Thomas O.
Published: July 2009

Defect structures associated with tin doping of indium oxide, an optically transparent conductor, have been characterized by atomistic simulations and first‐principles density functional calculations. A comprehensive survey of defect clusters containing up to three tin dopants in the first and second cationic coordination shells of an oxygen interstitial has been conducted. The analysis of energetically favorable defects gives insights into the role and nature of defect clusters in the material. In particular, the origins of the experimentally postulated b‐site preference of tin dopants have been examined. Our results show that b‐site preference occurs only in defect clusters with oxygen interstitials and is not intrinsic to dopants. In contrast, in nearest coordination to an interstitial, a strong d‐site preference is found. Density functional calculations in the discrete variational‐embedded cluster approximation have been conducted on selected defect structures to illuminate the effect of clustering on partial atomic charges, bond‐orders, and 119Sn Mössbauer parameters.
Defect Cluster Aggregation and Nonreducibility in Tin‐Doped Indium Oxide
Authors: Warschkow Oliver , Ellis Donald E. , González Gabriela B. , Mason Thomas O.
Published: July 2009

The conductivity of tin‐doped indium oxide (ITO), a transparent conductor, is critically dependent on the amount of tin doping and oxygen partial pressure during preparation and annealing. Frank and Köstlin (Appl. Phys. A, 27, 197–206 (1982)) have rationalized the observed carrier concentration dependence by postulating the formation of two types of neutral defect clusters at medium tin‐doping levels: “reducible” and “nonreducible” defect clusters, so named to indicate their ability to create carriers under reduction. According to Frank and Köstlin, both clusters are composed of one oxygen interstitial and two tin atoms substituting for indium, positioned in nonnearest and nearest coordination, respectively. This work, seeking to distinguish reducible and nonreducible clusters by means of an atomistic model, finds only a weak correlation of oxygen interstitial binding energies with the relative positioning of tin dopants. Instead, the number of tin dopants in the vicinity of the interstitial has a much larger effect on how strongly it is bound, a simple consequence of Coulomb interactions. We postulate that oxygen interstitials become nonreducible when clustered with three or more SnIn. This occurs at higher doping levels as reducible clusters aggregate and share tin atoms. A simple probabilistic model, estimating the average number of clusters so aggregated, yields a qualitatively correct description of the carrier density in reduced ITO as a function of tin‐doping level.
High‐Temperature Resistant Composites in the AlN–SiC–MoSi2 System
Authors: Sciti Diletta , Guicciardi Stefano , Melandri Cesare , Bellosi Alida
Published: July 2009

Two fully dense composites containing AlN, SiC, and MoSi2 in different amounts were produced by hot pressing. Young modulus, hardness, electrical conductivity, and thermal expansion coefficient were measured at room temperature. Strength and toughness were evaluated up to 1300°C in air. According to statistical analysis, the temperature has little or no effect on high‐temperature fracture behavior of the composites. These electroconductive materials are suitable for thermomechanical applications at high temperature, the strength being about 600 MPa at 1300°C.
Thermochemistry of Glasses in the Y2O3‐Al2O3‐SiO2 System
Authors: Zhang Yahong , Navrotsky Alexandra
Published: July 2009

Enthalpies of drop solution in molten 2PbO‐B2O3 at 1078 K were measured for glasses along the 2YAlO3‐3SiO2 and return ½Y3Al5O12‐3SiO2 joins. The onset glass transition temperature increases slightly with increasing silica content and Y/Al. Enthalpies of mixing were calculated on the basis of amorphous end members. Strongly negative heats of mixing support the absence of miscibility gaps except possibly for very high silica content, consistent with experimental phase analyses, which indicate much narrower miscibility gaps compared with the phase diagrams calculated on the basis of previous data and the CALPHAD formalism.
Molecular Dynamics Simulations of Calcium Silicate Intergranular Films between Silicon Nitride Crystals
Authors: Garofalini Stephen H. , Luo Weiwei
Published: July 2009

Molecular dynamics simulations were used to study the structure of calcium silicate intergranular films (IGFs) formed between the basal planes of silicon nitride crystals. A multibody potential was used to describe the interactions between ions. Samples with different film thickness and CaO contents were studied. Epitaxial adsorption of Si and O atoms from the intergranular films onto N and Si, respectively, in the crystal surface was observed. This epitaxial order induced a structural order into the nominally amorphous IGF that decreased as a function of distance from the IGF/crystal interface. A higher concentration of strained siloxane bonds was observed at the IGF/crystal interface in comparison to the amorphous interior of the IGF. While Ca ions were observed to segregate to the IGF/crystal interface in simulations of calcium silicate glass IGFs between alumina crystals, no segregation of calcium to the first adsorbed layer on the nitride was found in these simulations using silicon nitride crystals. Planar alignment of Ca ions parallel to the IGF/crystal interface occurred with either the largest concentrations of CaO or with the thinnest IGFs studied here. This alignment creates localized nonbridging oxygen that would affect the stability of the IGF/crystal system.
Nanostructures at Electrostatic Bond Interfaces
Authors: van Helvoort Antonius T. J. , Knowles Kevin M. , Fernie John A.
Published: July 2009

During electrostatic bonding of aluminum to Pyrex glass, γ‐Al2O3 is formed on the interface between the two materials in two distinct morphologies. The first, and more obvious, morphology is that of highly textured nanocrystalline structures growing from the interface into the glass. These nanostructures have a distinct effect on the width of the sodium‐depletion layer formed in the glass and are associated with precipitates in the aluminum adjacent to the aluminum/Pyrex interface. The second morphology of γ‐Al2O3 is an anodic oxide layer on the interface between the two materials. Together, these two morphologies enable strong bonds to be made.
Atomic Resolution Transmission Electron Microscopy of the Intergranular Structure of a Y2O3‐Containing Silicon Nitride Ceramic
Authors: Ziegler A. , Kisielowski C. , Hoffmann M. J. , Ritchie R. O.
Published: July 2009

High‐resolution transmission electron microscopy (HRTEM) employing focus‐variation phase‐reconstruction methods is used to image the atomic structure of grain boundaries in a silicon nitride ceramic at subangstrom resolution. Complementary energy‐dispersive X‐ray emission spectroscopy experiments revealed the presence of yttrium ions segregated to the 0.5–0.7‐nm thin amorphous boundary layers that separate individual grains. Our objective here is probing if yttrium ions attach to the prismatic planes of the Si3N4 at the interface toward the amorphous layer, using Scherzer and phase‐reconstruction imaging, as well as image simulation. Crystal structure images of grain boundaries in thin sample (<100 Å) areas do not reveal the attachment of yttrium at these positions, although lattice images from thicker areas do suggest the presence of yttrium at these sites. It is concluded that most of the yttrium atoms are located in the amorphous phase and only a few atoms may attach to the terminating prism plane. In this case, the line concentrations of such yttrium in the latter location are estimated to be at most one yttrium atom every 17 Å.
A New Glycothermal Process for Barium Titanate Nanoparticle Synthesis
Authors: Kim Byoung‐Kyu , Lim Dae‐Young , Riman Richard E. , Nho Jun‐Seok , Cho Seung‐Beom
Published: July 2009

Barium titanate (BaTiO3) nanoparticles were synthesized at the low temperature of 80°C through a glycothermal reaction using Ba(OH)2·8H2O and amorphous titanium hydrous gel as precursors and a solution of 1,4‐butanediol and water as solvent. This processing method provides a simple low‐temperature route for producing BaTiO3 nanoparticles, which could also be extended to other systems. It is demonstrated that the size of BaTiO3 particles can be controlled by reaction conditions, such as reaction temperature and various volume ratios of 1,4‐butanediol/water.
Preparation of Dense MgB2 Bulk Superconductors by Spark Plasma Sintering
Authors: Lee Soo‐Yong , Yoo Sang‐Im , Kim Young‐Woon , Hwang Nong M. , Kim Doh‐Yeon
Published: July 2009

Fully dense MgB2 bulk specimens (∼higher than 99% dense) were prepared using spark plasma sintering (SPS) at 1250°C for 15 min. Microstructure analyses revealed that faceted MgO particles of ∼8% volume fraction were dispersed in the MgB2 matrix. A sharp superconducting transition with an onset temperature of 38.5 K was confirmed by both magnetization and resistivity measurements.
Undercooled Melt Formation and Shaping of Alumina–Yttrium Aluminum Garnet Eutectic Ceramics
Authors: Yasuda Hideyuki , Mizutani Yoshiki , Ohnaka Itsuo , Sugiyama Akira , Morikawa Takashi , Waku Yoshiharu
Published: July 2009

Undercooled melt was produced in the alumina‐rich portion of the Al2O3–Y2O3 system, heating the metastable eutectic structure to above the metastable eutectic temperature but below the equilibrium eutectic temperature, followed immediately by solidification along the equilibrium path in the undercooled melt. Coupling the melting and solidification enabled a nearly adiabatic transformation from the metastable eutectic structure to the equilibrium eutectic structure. The eutectic structure produced through the solidification was uniform and fine throughout the castings. A fin‐type casting with a thickness of 300 μm was successfully produced. This paper proposes a novel casting process using the undercooled melt formation.
No evidence of abnormal regulation of antibody response to coxsackievirus B4 antigen in prediabetic children
Authors: Heino L , Lönnrot M , Knip M , Kupila A , Erkkilä S , Toivonen A , Vähäsalo P , Ilonen J , Simell O , Hyöty H
Published: July 2009

Enterovirus infections are a potential environmental trigger of the autoimmune process leading to clinical type 1 diabetes. It has been suggested that the risk of virus-induced beta-cell damage might be connected with a defect in humoral immune responsiveness to enteroviruses. In the present study we assessed whether such a defect in IgG responsiveness to coxsackievirus B4 antigen existed in young children who developed diabetes-associated autoantibodies during prospective observation from birth until the age of 18 months. IgG levels and maturation of antibody avidity were analysed in 21 children with autoantibodies and 41 control children who had experienced an equal number of enterovirus infections and were additionally matched for age, sex and HLA-DQB1 risk alleles for type 1 diabetes but had not produced diabetes-associated autoantibodies. IgG levels to coxsackievirus B4 were high in cord serum reflecting the presence of maternal antibodies. Mean IgG levels gradually decreased but began to increase after the age of 6 months, showing no significant difference between autoantibody positive and control children. The avidity of antibodies was strong in cord serum and decreased gradually during the first year of life when maternal antibodies disappeared. The avidity indices, which varied considerably from child to child, did not differ between the autoantibody-positive and -negative subjects. In conclusion, our data suggest that children affected by a beta-cell damaging autoimmune process show normal responses to coxsackievirus B4 antigens.
Four different NCF2 mutations in six families from Turkey and an overview of NCF2 gene mutations
Authors: Köker M. Y. , Sanal Ö. , Van Leeuwen K. , De Boer M. , Metin A. , Patıroğlu T. , Özgür T. T. , Tezcan I. , Roos D.
Published: July 2009

Background  One of the rarest forms of autosomal recessive chronic granulomatous disease (AR‐CGD) is attributable to mutations in the NCF2 gene, which encodes the polypeptide p67phox, a key cytoplasmic protein in the phagocyte NADPH oxidase system. NCF2 is localized on chromosome 1q25, encompasses 40 kb and contains 16 exons.

Materials and methods  We report here the clinical and molecular characterization of six patients with CGD from six consanguineous Turkish families. The ages of the five female patients were between 3 and 22 years and a male patient was 2 years old; all patients showed clear clinical symptoms of CGD.

Results  The mothers of the patients did not show a bimodal histogram pattern specific for X‐CGD in the dihydrorhodamine‐1,2,3 (DHR) assay. Moreover, p67phox protein expression was not detectable using flow cytometric analysis of the patients’ neutrophils except in those from patient 6, which had a diminished expression. Mutation analysis of NCF2 revealed four different homozygous mutations: a novel nonsense mutation in exon 3 c.229C>T, p.Arg77X; a novel missense mutation in exon 4 c.279C>G, p.Asp93Glu; a nonsense mutation in exon 4 c.304C>T, p.Arg102X; and a novel missense mutation in exon 6 c.605C>T, p.Ala202Val. The parents were found to be heterozygotes for these mutations.

Conclusions  The prevalence of NCF2 mutant families is approximately 15% in our series of 40 CGD families. This high incidence of A67 CGD in Turkey is undoubtedly caused by the high incidence of consanguineous marriages. We found three new mutations in NCF2 and one previously described. These are presented together with an overview of all NCF2 mutations now known.
Functional analysis of GS28, an intra‐Golgi SNARE, in Caenorhabditis elegans
Authors: Maekawa Masashi , Inoue Takao , Kobuna Hiroyuki , Nishimura Taki , Gengyo‐Ando Keiko , Mitani Shohei , Arai Hiroyuki
Published: July 2009

Intra‐Golgi retrograde transport is assumed to maintain Golgi function by recycling Golgi‐resident proteins to younger cisternae in the progression of entire Golgi stack from cis to trans. GS28 (Golgi SNARE of 28 kDa, also known as GOS28) is a Golgi‐localized SNARE protein and has been implicated in intra‐Golgi retrograde transport. However, the in vivo functions of GS28, and consequently, the roles of the intra‐Golgi retrograde transport in animal development are largely unknown. In this study, we generated deletion mutants of Caenorhabditis elegans GS28 and performed a synthetic lethal RNAi screen using GS28 mutants. We found that another Golgi‐localized SNARE, Ykt6, functions cooperatively with GS28 in embryonic development. During post‐embryonic development, GS28 mutants exhibited reduced seam cell numbers and a missing ray phenotype under Ykt6 knockdown conditions, suggesting that cell proliferation and/or differentiation of stem cell‐like seam cells are impaired in GS28‐ and Ykt6‐depleted worms. We also demonstrated that GS28 and Ykt6 act redundantly for the proper expression of Golgi‐resident proteins in adult intestinal cells. This study reveals the in vivo importance of the Golgi‐localized SNAREs GS28 and Ykt6.
Digital imaging and public engagement in palaeontology
Authors: Bates Karl T. , Falkingham Peter L. , Hodgetts David , Farlow James O. , Breithaupt Brent H. , O'Brien Mike , Matthews Neffra , Sellers William I. , Manning Phillip L.
Published: July 2009

Public engagement and the promotion of science to a wider non‐academic audience form an integral role of the professional scientist in the twenty‐first century. The high level of public interest in palaeontology means that the Earth's prehistoric past can provide an important medium through which to communicate information concerning contemporary scientific issues. Here we explain how modern computer techniques can be used to enhance public understanding of complex palaeontological issues.
Barbados
Authors: Donovan Stephen K. , Harper David A.T.
Published: July 2009

In the words of the noted Antillean geologist C.T. Trechmann (1937, p.337), ‘Barbados, 21 miles long, 14 miles wide, rising to 1101 feet, is probably the most considerable Pleistocene non‐volcanic bleb on the face of our planet, at least in the Antillean region.’ The island's geology shows a stark contrast between the allochthonous siliciclastic succession of an accretionary prism, deposited in water depths measurable in kilometres, and the autochthonous Pleistocene raised reef cap exposed over 90 per cent of Barbados.
Changes in the abundance of C3/C4 species of Inner Mongolia grassland: evidence from isotopic composition of soil and vegetation
Authors: WITTMER MAXIMILIAN H. O. M. , AUERSWALD KARL , BAI YONGFEI , SCHÄUFELE RUDI , SCHNYDER HANS
Published: July 2009

Global warming, increasing CO2 concentration, and environmental disturbances affect grassland communities throughout the world. Here, we report on variations in the C3/C4 pattern of Inner Mongolian grassland derived from soil and vegetation. Soil samples from 149 sites covering an area of approximately 250 000 km2 within Inner Mongolia, People's Republic of China were analyzed for the isotopic composition (δ13C) of soil organic carbon (SOC). The contrast in δ13C between C3 and C4 plants allowed for calculation of the C3/C4 ratio from δ13C of SOC with a two‐member mixing model, which accounted for influences of aridity and altitude on δ13C of the C3 end‐member and for changes in δ13C of atmospheric CO2. Maps were created geostatistically, and showed a substantially lower C4 abundance in soil than in recent vegetation (−10%). The difference between soil and vegetation varied regionally and was most pronounced within an E–W belt along 44°N and in a mountainous area, suggesting a spread of C4 plants toward northern latitudes (about 1°) and higher altitudes. The areas of high C4 abundance for present vegetation and SOC were well delineated by the isotherms of crossover temperature based on the climatic conditions of the respective time periods. Our study indicates that change in the patterns of C3/C4 composition in the Inner Mongolia grassland was mainly triggered by increasing temperature, which overrode the antagonistic effect of rising CO2 concentrations.
A rapid HPLC‐determination of ATP‐related compounds and its application to herring stored under modified atmosphere
Authors: Özogul Fatih , Taylor K. D. Anthony , Quantick Peter C. , Özogul Yesim
Published: July 2009

A high performance liquid chromatography (HPLC) method was developed by using gradient elution with acetonitrile as a mobile phase to reduce the time required for determination of ATP, ADP, AMP, IMP, HxR and Hx. The method was then applied to investigate nucleotide degradation in herring kept in ice and MAP (60% CO2/40% N2).
Production and properties of a semi‐hard cheese made from soya milk
Authors: Chumchuere Sumonwan , MacDougall Douglas B. , Robinson Richard K.
Published: July 2009

SummaryA semi‐hard soya cheese, with mean moisture content 61.5%, crude protein 21.8% and fat 2.6%, was produced from reconstituted soya‐milk powder using a starter culture ofStreptococcus thermophilusandLactobacillus fermentum. The physical properties of the cheese, as determined with a Texture Profile Analyser, were similar to a cheese made to the same compositional standards from bovine milk. A taste panel of Far Eastern subjects did not find the flavour of the fresh soya cheese acceptable but, when cubes of the cheese (1 cm3) were deep‐fried in corn oil, the hedonic rating improved significantly. It is suggested that the cheese could be used as a protein‐rich component of a meal, e.g. to replace meat in a stew, or as a ‘snack food’.
Immersion chilling and freezing of a porous medium
Authors: Lucas Tiphaine , Favier Claude , Chourot Jean‐Marc , Guilpart Jacques , Raoult‐Wack Anne‐Lucie , Aïm Roger B.
Published: July 2009

An experimental apparatus, putting one face of a water‐saturated glass bead bed in contact with a high‐concentration (23% NaCl) aqueous freezant (the other face being insulated against heat and mass transfer), was constructed to simultaneous study heat and mass transfer at the product/solution interface and within the product more closely than is possible in real foods. The selected flow allowed uniform heat treatment (a constant heat transfer coefficient) over a large part of the product. The apparatus was used to monitor three elements within the product: the temperature profiles, the NaCl concentration profiles for the liquid phase and the freezing and thawing fronts. The first results showed that a surface layer of a highly impregnated non‐frozen product was present at the end of freezing. If the frozen product was left in contact with the refrigerating solution, progressive thawing occurred from the surface inwards; thawed layer thickness seemed to be a linear function of the square root of time.
Use of the single cell gel electrophoresis assay (Comet assay) as a technique for monitoring low‐temperature treated and  irradiated muscle tissues
Authors: Park Jong‐Heum , Hyun Chang‐Kee , Jeong Seok‐Kyu , Yi Mi‐Ae , Ji Seung‐Taek , Shin Heuyn‐Kil
Published: July 2009

The influence of refrigeration, freezing, repetitive freezing‐thawing, and irradiation on meat quality were evaluated by detecting DNA damage to beef muscle tissues using the single cell gel electrophoresis assay (Comet assay). Comet tail lengths indicating DNA damage levels increased with refrigeration time up to 10 days. In the case of frozen storage, the damage was increased only for the first 15 days of storage, but after that, decreased slightly and the tail lengths at 15 days were similar to those of 3˜5 days refrigerated storage. Tail lengths resulting from repetitive freezing‐thawing were increased after two cycles of treatment and three cycles produced longer tails than those that had been refrigerated for 10 days or kept in frozen storage for 60 days. Irradiation from 1 to 10 kGy caused the most serious DNA damage among the treatments compared in this study. The two kinds of muscle tissue were similar in the pattern of results obtained from the Comet assay. The mean tail length of the comets reflected approximately the increasing patterns of DNA damage, but the differences of values between the extents of treatment were somewhat insignificant and anomalous. Therefore, we used the concept of relative damage index (RDI) calculated from per cent cells data for each tail length range and representing a state of DNA damage. Significantly different values in RDI’s made it possible to discriminate samples according to the treatment levels within each treatment.
A databank able to be used for identifying and authenticating commercial flatfish (Pleuronectiformes) products at the species level using isoelectric focusing of native muscle proteins
Authors: Bossier Peter , Cooreman Kris
Published: July 2009

Summary A computerized databank of IEF protein patterns for use in identifying flatfish species (in total 17 species, including 15 commercial ones) is presented. The databank includes all species regulated by the Belgian Law (22 May 1996) on the use of official names for fishes and seafood products. It was found that interspecimen similarity of the IEF patterns, as processed by digitization, was always larger than interspecies similarity, which allows for unequivocal authentication of unknown samples, as long as the authentic pattern is available in the databank. The databank was used to authenticate 17 commercial fish fillets.
A robust method for processing scanning probe microscopy images and determining nanoobject position and dimensions
Authors: SILLY F.
Published: July 2009

Processing of scanning probe microscopy (SPM) images is essential to explore nanoscale phenomena. Image processing and pattern recognition techniques are developed to improve the accuracy and consistency of nanoobject and surface characterization. We present a robust and versatile method to process SPM images and reproducibly estimate nanoobject position and dimensions. This method is using dedicated fits based on the least‐square method and the matrix operations. The corresponding algorithms have been implemented in the FabViewer portable application. We illustrate how these algorithms permit not only to correct SPM images but also to precisely determine the position and dimensions of nanocrystals and adatoms on surface. A robustness test is successfully performed using distorted SPM images.
Cytoplasmic membrane protonmotive force energizes periplasmic interactions between ExbD and TonB
Authors: Ollis Anne A. , Manning Marta , Held Kiara G. , Postle Kathleen
Published: July 2009

The TonB system of Escherichia coli (TonB/ExbB/ExbD) transduces the protonmotive force (pmf) of the cytoplasmic membrane to drive active transport by high‐affinity outer membrane transporters. In this study, chromosomally encoded ExbD formed formaldehyde‐linked complexes with TonB, ExbB and itself (homodimers) in vivo. Pmf was required for detectable cross‐linking between TonB–ExbD periplasmic domains. Consistent with that observation, the presence of inactivating transmembrane domain mutations ExbD(D25N) or TonB(H20A) also prevented efficient formaldehyde cross‐linking between ExbD and TonB. A specific site of periplasmic interaction occurred between ExbD(A92C) and TonB(A150C) and required functional transmembrane domains in both proteins. Conversely, neither TonB, ExbB nor pmf were required for ExbD dimer formation. These data suggest two possible models where either dynamic complex formation occurred through transmembrane domains or the transmembrane domains of ExbD and TonB configure their respective periplasmic domains. Analysis of T7‐tagged ExbD with anti‐ExbD antibodies revealed that a T7 tag was responsible both for our previous failure to detect T7–ExbD–ExbB and T7–ExbD–TonB formaldehyde‐linked complexes and for the concomitant artefactual appearance of T7–ExbD trimers.
Variation in larval chaetotaxy inOrthosia gothica(Lepidoptera: Noctuidae): effects of mother, sex and side, and implications for systematics
Authors: MUTANEN MARKO , RUOTSALAINEN HANNE , KAILA LAURI
Published: July 2009

Insect larval characteristics, including chaetotaxy, are used widely in systematics, including for classification and phylogenetic reconstruction. Despite their common use, basic aspects of larval morphology, including intraspecific variation, effects of relatedness between individuals, sex and asymmetry, are little investigated. In the larvae of the noctuid mothOrthosia gothica, properties of shape and size were separated to examine their effects separately. Siblings were found not to cover the entire variation of a population, and therefore specimens originating from a single female do not represent independent samples. This methodological bias may potentially lead to wrong conclusions regarding species characteristics. We observed slight differences between the left and right sides of the specimens studied, implying that one side should be examined consistently in studying larval chaetotaxy. We found no differences between sexes, but this may apply only to the species examined here; in general, sex should be determined and accounted for. We discovered considerable variation in seta numbers, which further emphasizes the importance of sufficient material, particularly in cladistic analyses in which setal counts are often used as characters.
IgE cross‐reactivity between Ascaris and domestic mite allergens: the role of tropomyosin and the nematode polyprotein ABA‐1
Authors: Acevedo N. , Sánchez J. , Erler A. , Mercado D. , Briza P. , Kennedy M. , Fernandez A. , Gutierrez M. , Chua K. Y. , Cheong N. , Jiménez S. , Puerta L. , Caraballo L.
Published: July 2009

Background:  Analysis of cross‐reactivity between the nematode Ascaris ssp. and dust mites, two important allergen sources in the tropics, will contribute in understanding their influence on asthma and atopy. The objective of this study was to investigate immunoglobulin E (IgE) cross‐reactivity between Ascaris and two domestic mites in the tropics.

Methods:  Sera from 24 asthmatic patients were used in ELISA and immunoblotting IgE‐binding inhibition assays using Ascaris, Blomia tropicalis and Dermatophagoides pteronyssinus extracts and the recombinants Blo t 10, ABA‐1 and Blo t 13 as competitors. Identification of Ascaris allergens was confirmed by mass spectrometry (LC‐MS/MS).

Results:  We detected at least 12 human IgE‐binding components in Ascaris extract. Blomia tropicalis and D. pteronyssinus inhibited 83.3% and 79% of IgE‐binding to Ascaris, while Ascaris inhibited 58.3% and 79.3% to B. tropicalis and D. pteronyssinus respectively. Mite tropomyosin inhibited 85% of IgE‐binding to Ascaris. Affinity‐purified human IgE to rBlo t 10 identified an allergen of 40 kDa in Ascaris extract, further confirmed as tropomyosin by LC‐MS/MS. We found no evidence of IgE cross‐reactivity between rABA‐1 and any allergen component in mite extracts, including rBlo t 13.

Conclusions:  There is cross‐reactivity between Ascaris and mites, determined by several allergens including tropomyosin and glutathione‐S‐transferase. In addition to its potential impact on asthma pathogenesis, Ascaris infection and mite allergy diagnosis relying on the determination of specific IgE could be affected by this cross‐reactivity. ABA‐1 has no cross‐reactive counterpart in mite extracts, suggesting its usefulness as a more specific marker of Ascaris infection.