bluuebunny/crossref_metadata_2025 huggingface dataset:
Postgraduate Symposium The role of fat in gastric emptying and satiety: acute and chronic effects
Authors: Clegg Miriam , Shafat Amir
Published: January 2009

Dietary fat is an important factor in the aetiology of obesity and the metabolic syndrome. It has been widely debated whether gastric emptying (GE) is altered in obesity. GE times have been reported as both longer and shorter in obese individuals compared with matched lean individuals. However, the general consensus is that GE is accelerated and satiety is lower in obesity. Research has implicated a high-fat (HF) diet in these findings. A single HF meal has a longer GE time than a low-fat meal and can even delay GE of the subsequent meal. However, an HF diet has shown different effects. Feeding a HF diet adapts gastrointestinal function to reduce GE times in comparison with a low-fat diet. Increased GE may lead to decreased satiety and faster onset of subsequent eating episodes. Further results have suggested that consuming an HF diet for 14 d increases the GE rate of HF food but not low-fat food. Consuming HF diets for 2 weeks has also been shown to increase food intake. Decreased satiation following an HF diet may cause increased food intake and a positive energy balance, potentially resulting in a gradual increase in adiposity. Recent results have suggested that gastrointestinal transit is accelerated following only 3 d on a HF diet. The variable GE times reported in obesity may be associated with interactions between the HF diet and obesity and not simply the obese state.
Health-related quality of life measures in routine clinical care: Can FACT-Fatigue help to assess the management of fatigue in cancer patients?
Authors: Santana Maria-Jose , Au Heather-Jane , Dharma-Wardene Melina , Hewitt Joanne D. , Dupere David , Hanson John , Ghosh Sunita , Feeny David
Published: January 2009

Objectives:Fatigue is the most common symptom reported by cancer patients. The inclusion of health-related quality of life (HRQL) measures in routine clinical care of cancer patients may improve the management of fatigue. The primary objective of this study is to provide evidence on the magnitude of change in fatigue subscale scores using the Functional Assessment of Cancer Therapy-Fatigue (FACT-F) that is clinically important.

Methods:Consecutive patients with advanced primary lung cancer attending a Canadian tertiary care cancer and, prior to undergoing palliative chemotherapy, were enrolled in the study. Patients completed a battery of questionnaires [FACT-F, Qualitative Patients Self-report of Fatigue Level (QPSRF)] at baseline, follow-up and 2 weeks after their final cycle of chemotherapy. Clinicians assessed the patients using the Eastern Cooperative Oncology Group (ECOG) Performance Status Scale at baseline and each follow-up visit. FACT-F change scores were computed as the mean change in score (end of study score minus baseline score).

Results:A total of 43 patients with mean age of 59 years were enrolled in the study. Results revealed a mean change in FACT-F subscale score of 5.0 (SE 1.06) for those who rated themselves as more tired, 1.28 (SE 1.00) for those who rated themselves as the same (no change), and −1.52 (SE 0.84) for those patients who rated themselves as less tired.

Conclusions:We provide evidence on the magnitude of change in FACT-F score that is associated with the perception by patients of improvement in fatigue and magnitude of change in score that is associated with worsening in fatigue.
Information technology capacities assessment tool in hospitals: Instrument development and validation
Authors: Jaana Mirou , Paré Guy , Sicotte Claude
Published: January 2009

Objectives:This research integrates existing literature on information technology (IT) in hospitals, and proposes and validates a comprehensive IT capacities assessment tool in these settings.

Methods:A comprehensive literature review was conducted on Medline until September 2006 to identify studies that used specific IT measures in hospitals. The results were mapped and used as a basis for the development of the proposed instrument, which was tested through a survey of Canadian healthcare organizations (N= 221).

Results:A total of seventeen studies provided indicators of clinical and administrative IT capacities in hospitals. Based on the mapping of these indicators, a comprehensive IT capacities assessment instrument was developed including thirty-four items exploring computerized processes, thirteen items assessing contemporary technologies, and eleven items investigating internal and external information sharing. A time frame was inserted in the tool to reflect “plans for” versus “current” implementation of IT; in the latter, the extent of current use of computerized processes and technologies was measured on a (1–7) scale. Overall, the survey yielded a total of 106 responses (52.2 percent response rate), and the results demonstrated a good level of reliability and validity of the instrument.

Conclusions:This study unifies existing work in this area, and presents the psychometric properties of an IT capacities assessment tool in hospitals. By developing scores for capturing IT capacities in hospitals, it is possible to further address important research questions related to the determinants and impacts of IT sophistication in these settings.
Sound recording and the end of the Italian Lohengrin
Authors: MEYER STEPHEN C.
Published: January 2009

This article compares early and mid twentieth-century Italian-language recordings of Lohengrin excerpts with German-language recordings of the same period. The production and distribution of Italian-language recordings in the United States is an extension of nineteenth-century practices, in which ‘national styles’ of singing were detachable from specific repertoires. Preserving characteristic vocal inflections and distinctive interpretations, these recordings give insight into the intersections and conflicts between the various national performing traditions that were so important to nineteenth-century operatic life. The interpretative diversity of these recordings is an index of the extent to which performance traditions and individual character were markers of cultural (and economic) value in the first decades of the twentieth century. Focusing on Elsa’s Dream and the Grail Narration, I show how this interpretative diversity declined dramatically during the course of the twentieth century. This decline was precipitated by a number of factors, including the introduction of the LP disc in 1948. But the decline of the Italian Lohengrin also attests to a paradigm shift essential to the reception of classical music in the United States: from the idea that the recording is a reproduction of a voice to one in which it functions primarily as a realization of the composer’s score.
Minimalism and French /ʀ/: Phonological representations in phonetically based phonology
Authors: WEBB ERIC RUSSELL
Published: January 2009

This paper examines the phonological structure of French rhotics and their treatment in a production grammar. Assuming emergent featural specification, it is argued that the underlying representation of /ʀ/ contains only values for sonorance, continuance and place of articulation. Grammatical analysis is undertaken in an Optimality Theoretic framework, where evaluation highlights the effect of effort reduction and perceptual augmentation on /ʀ/, also demonstrating that more richly specified segments are unaffected by these constraints. The proposal is shown to be compatible with antecedent analyses and data from regional forms and registers.
Inversion of the “Unrealistic Optimism” Bias Contributes to Overestimation of Threat in Obsessive-Compulsive Disorder
Authors: Moritz Steffen , Jelinek Lena
Published: January 2009

Background: Overestimation of threat (OET) is ascribed a pathogenetic role in obsessive-compulsive disorder (OCD). Aims: We hypothesized that OCD patients overestimate their personal but not the average risk for OCD-related events. Specifically, an attenuation of the common “unrealistic optimism” bias (UO) was expected for OCD patients. UO refers to the phenomenon that the subjective likelihood to personally experience a positive event is enhanced compared to other persons and vice versa for negative events. Method: Fifty-three participants with OCD as well as 40 healthy and 23 psychiatric controls participated in an internet survey. They were asked several questions about different event types (positive, negative, and OCD-related): the probability that this event will happen to oneself (block 1), to another person (block 2), comparison between oneself versus another person (block 3), appraisal of consequences (block 4), and prior encounters with event (block 5). Results: No evidence was obtained in OCD to overestimate the overall probability of negative or OCD-related events. However, whereas healthy participants displayed an UO bias, OCD participants perceived themselves as more vulnerable to experience OCD-related events. Conclusions: Results indicate that OCD is associated with inflated personal vulnerability and that this bias is not fully available to the consciousness of OCD participants.
Effects observed in the Latin American sector ionospheric F region during the intense geomagnetic disturbances in the early part of November 2004
Authors: Sahai Y. , Becker‐Guedes F. , Fagundes P. R. , de Jesus R. , de Abreu A. J. , Paxton L. J. , Goncharenko L. P. , Brunini C. , Gende M. , Ferreira A. S. , Lima N. S. , Guarnieri F. L. , Pillat V. G. , Bittencourt J. A. , Candido C. M. N.
Published: January 2009

The Sun was very active in the early part of November 2004. During the period of 8–10 November 2004, intense geomagnetic disturbances with two superstorms were observed. In this paper, we have investigated the generation and suppression of equatorial ionospheric irregularities and the daytime changes in the F region electron density in the Latin American sector during the period of intense geomagnetic disturbances. We present the ionospheric sounding observations carried out at Manaus and Sao Jose dos Campos, Brazil, during this geomagnetically disturbed period. Also, GPS observations obtained from several stations in Brazil, Argentina, and St. Croix, U.S. Virgin Islands, during the disturbed period are presented. During the main phase of the first superstorm, around the prereversal enhancement time (night of 7–8 November), prompt penetration of electric field was observed and the presence of equatorial ionospheric irregularities was detected from St. Croix, U.S. Virgin Islands (in the northern hemisphere) to Bahia Blanca, Argentina (in the southern hemisphere). The ionospheric sounding observations at Manaus indicate inhibition of prereversal enhancement on the nights of 9–10 and 10–11 November, possibly due to the disturbed thermospheric winds or disturbance electric fields. Virtually no phase fluctuations on the nights of 9–10 and 10–11 November were observed in the Latin American sector. During the daytime on 8 November, the vertical total electron content (VTEC) observations show a negative storm phase at Porto Alegre (Brazil) and Bahia Blanca (Argentina). Again during the daytime on 10 November, the VTEC observations show a negative storm phase from Brasilia (Brazil) to Bahia Blanca. These negative storm phases are associated with a decrease in the O/N2 ratio. During the daytime on 9 November, the VTEC observations show a positive storm phase extending from St. Croix to Porto Alegre, and again on 10 November, VTEC observations show a positive storm phase. These positive storm phases observed are possibly due to changes in large‐scale wind circulation and an increase in the O/N2 ratio.
Role of aircraft soot emissions in contrail formation
Authors: Kärcher B. , Yu F.
Published: January 2009

The susceptibility of microphysical properties of young contrails to changes in aircraft soot emissions is studied with a microphysical plume model. Liquid plume and ambient particles compete with exhaust soot particles for the formation of contrail ice particles, assuming that soot particles are activated into water droplets prior to homogeneous freezing. Soot controls ice formation in contrails for high number emission indices including the range of current global fleet values. A fivefold reduction of soot emissions from average levels of 5 × 1014 − 1015 (kg‐fuel)−1 approximately halves the initial contrail visible optical depth. Further soot reduction reverses this trend at temperatures well below the formation threshold temperature unless emissions of sulfur and organics are cut substantially. Whether and to which degree reductions in soot emissions help mitigate the contrail climate impact depends on subsequent aircraft wake vortex processing of contrails and their development into contrail cirrus.
Development of affinity columns for the removal of high‐abundance proteins in cerebrospinal fluid
Authors: Ramström Margareta , Zuberovic Aida , Grönwall Caroline , Hanrieder Jörg , Bergquist Jonas , Hober Sophia
Published: January 2009

Various approaches for removal of high‐abundance components in body fluids are currently available. While most methods are constructed for plasma depletion, there is a need for body‐fluid‐specific strategies. The aim of the present study was to design an affinity matrix suitable for the depletion of high‐abundance proteins in CSF (cerebrospinal fluid). Hence, molecules with specific affinity towards proteins present at high concentration in CSF were desired. Affibody® molecules are specific binders of small size that have shown high stability under various conditions and are therefore good candidates for such a matrix. The protein composition in CSF resembles that in plasma. However, 20% of the proteins are brain‐derived and are therefore present in higher proportions in CSF than in plasma, whereas larger plasma‐derived proteins are less abundant in CSF. Therefore five high‐abundance CSF proteins were chosen for the design of a CSF‐specific depletion setup. Affibody® molecules with specificity towards HSA (human serum albumin), IgG, transferrin and transthyretin were combined in an affinity column. In addition, polyclonal antibodies against cystatin C were coupled to chromatographic beads and packed in a separate column. Highly reproducible and efficient removal of the five target proteins was observed. The proportion of depleted proteins were estimated to be 99, 95, 74, 92 and 83% for HSA, IgG, transferrin, transthyretin and cystatin C respectively. SDS/PAGE analysis was used for monitoring and identifying proteins in native CSF, depleted CSF samples and the captured fractions. Moreover, shotgun proteomics was used for protein identification in native as well as depleted CSF and the achieved data were compared. Enhanced identification of lower‐abundance components was observed in the depleted fraction, in terms of more detected peptides per protein.
Direct imaging reveals exoplanets in orbital motion
Authors: Schwarzschild Bertram
Published: January 2009

If a planet orbiting another star is young enough, the afterglow from its heat of formation may be adequate for imaging.
Applying Title IX to university science departments
Authors: Feder Toni
Published: January 2009

Some federal funding agencies are reviewing the treatment of female students and faculty members in university departments they fund. Can such spot checks lead the way to gender equity?
Panofsky agonistes: The 1950 loyalty oath at Berkeley
Authors: Jackson John David
Published: January 2009

In 1949–51 the University of California was seriously damaged by a loyalty-oath controversy. Wolfgang Panofsky, a promising young physics professor at Berkeley, was caught up in the turmoil.
Phytohormone-based activity mapping of insect herbivore-produced elicitors
Authors: Schmelz Eric A. , Engelberth Jurgen , Alborn Hans T. , Tumlinson James H. , Teal Peter E. A.
Published: January 2009

In response to insect attack, many plants exhibit dynamic biochemical changes, resulting in the induced production of direct and indirect defenses. Elicitors present in herbivore oral secretions are believed to positively regulate many inducible plant defenses; however, little is known about the specificity of elicitor recognition in plants. To investigate the phylogenic distribution of elicitor activity, we tested representatives from three different elicitor classes on the time course of defense-related phytohormone production, including ethylene (E), jasmonic acid (JA), and salicylic acid, in a range of plant species spanning angiosperm diversity. All families examined responded to at least one elicitor class with significant increases in E and JA production within 1 to 2 h after treatment, yet elicitation activity among species was highly idiosyncratic. The fatty-acid amino acid conjugate volicitin exhibited the widest range of phytohormone and volatile inducing activity, which spanned maize (
Zea mays
), soybean (
Glycine max
), and eggplant (
Solanum melongena
). In contrast, the activity of inceptin-related peptides, originally described in cowpea (
Vigna unguiculata
), was limited even within the Fabaceae. Similarly, caeliferin A16:0, a disulfooxy fatty acid from grasshoppers, was the only elicitor with demonstrable activity in
Arabidopsis thaliana
. Although precise mechanisms remain unknown, the unpredictable nature of elicitor activity between plant species supports the existence of specific receptor-ligand interactions mediating recognition. Despite the lack of an ideal plant model for studying the action of numerous elicitors, E and JA exist as highly conserved and readily quantifiable markers for future discoveries in this field.
Force amplification response of actin filaments under confined compression
Authors: Greene George W. , Anderson Travers H. , Zeng Hongbo , Zappone Bruno , Israelachvili Jacob N.
Published: January 2009

Actin protein is a major component of the cell cytoskeleton, and its ability to respond to external forces and generate propulsive forces through the polymerization of filaments is central to many cellular processes. The mechanisms governing actin's abilities are still not fully understood because of the difficulty in observing these processes at a molecular level. Here, we describe a technique for studying actin–surface interactions by using a surface forces apparatus that is able to directly visualize and quantify the collective forces generated when layers of noninterconnected, end-tethered actin filaments are confined between 2 (mica) surfaces. We also identify a force-response mechanism in which filaments not only stiffen under compression, which increases the bending modulus, but more importantly generates opposing forces that are larger than the compressive force. This elastic stiffening mechanism appears to require the presence of confining surfaces, enabling actin filaments to both sense and respond to compressive forces without additional mediating proteins, providing insight into the potential role compressive forces play in many actin and other motor protein-based phenomena.
Microstructure and Fracture Toughness of Si3N4 Ceramics: Combined Roles of Grain Morphology and Secondary Phase Chemistry
Authors: Kleebe Hans‐Joachim , Pezzotti Giuseppe , Ziegler Günter
Published: January 2009

Silicon nitride materials that contained different mixtures of sintering aids were investigated with respect to microstructure development and resulting fracture toughness. Postsintering annealing at 1850°C for various times was adopted in order to coarsen the respective microstructures. Although constant processing conditions were used, a marked variation in fracture toughness of the Si3N4 materials was evaluated. With a larger grain diameter of the Si3N4 grains, an increase in fracture resistance was generally observed. However, a correlation between fracture toughness and apparent aspect ratio could not be established. The observed changes in microstructure were in fact caused by the difference in secondary‐phase chemistry. Si3N4 grain growth was dominated by diffusion‐controlled Ostwald ripening and was hence affected by the viscosity of the liquid at processing temperature. In addition, crystallization at triple pockets also depends on the sintering additives employed and was found to influence fracture toughness by altering the crack‐propagation mode as a consequence of local residual microstresses at grain boundaries. The stress character (compressive vs tensile) is governed by the type of crystalline secondary phase formed. Moreover, a variation in interface chemistry changes the glass network structure on the atomic level, which can promote transgranular fracture, i.e., can result in a low fracture resistance even in the presence of favorable large Si3N4 matrix grains. Therefore, secondary‐phase chemistry plays a dominant role with respect to the mechanical behavior of liquid‐phase‐sintered Si3N4. Fracture toughness is, in particular, influenced by (i) altering the residual glass network structure, (ii) affecting the secondary‐phase crystallization at triple pockets, and (iii) changing the Si3N4 grain size/morphology by affecting the diffusion rate in the liquid. The first two effects of secondary‐phase chemistry are superimposed on the merely structural parameters such as grain diameter and apparent aspect ratio.
Phase Equilibria of the 1/2Bi2O3‐CaO System in Oxygen at 1 atm Pressure
Authors: Gökçen Oya A. , Styve Jason V. , Meen James K. , Elthon Don
Published: January 2009

Phase equilibria in the Bi2O3‐CaO system have been examined over the temperature range of 650°‐1050°C in oxygen at a pressure of 1 atm. Direct electron microprobe analysis has been used to determine the compositions of several phases with fixed Bi:Ca ratios and to determine the extents of compositional ranges of the three solid solutions in the system. The face‐centered‐cubic solid solution (FCCss) phase extends from pure Bi2O3 to a maximum CaO content of 27 mol% at 816°± 4°C. In the bismuth‐rich portion of the diagram, the FCCss phase is replaced by monoclinic Bi2O3 (which dissolves essentially no CaO) and a rhombohedral solid solution (Rhss) phase with 12 mol% CaO. The eutectoid is located at 6 mol% CaO and 684°± 3°C. A calcium‐rich FCCss phase also coexists at a eutectoid with a Rhss phase (23.5 mol% CaO) and Bi2CaO4 at 766°± 3°C. There are two two‐phase regions between the FCCss and Rhss phases that have a closure temperature that is estimated to be ∼840°C. The Rhss phase exists between these two‐phase regions. The minimum CaO content of this solid solution is 12 mol%, and its maximum CaO content is 23.5 mol%; however, the extent of solid solution is highly temperature dependent at >700°C. All liquids with 0‐23 mol% CaO may coexist with a FCCss phase. The stability field of the rhombohedral phase does not reach the solidus, and there is a thermal maximum on the liquidus that is estimated at ∼880°C at which a FCCss phase and a liquid phase, each with 17 mol% CaO, coexist. Liquid with 23 mol% CaO, a FCCss phase, and a body‐centered‐cubic solid solution (BCCss) phase with 27 mol% CaO coexist at a eutectic near 866°C. The BCCss phase has a maximum composition range of 27‐42 mol% CaO, although the range is dependent on temperature. At temperatures below 816°± 4°C, the BCCss phase is replaced by a FCCss phase and Bi6Ca4O13. At 970 ± 3°C, the BCCss phase with 42 mol% CaO melts incongruently to CaO and a liquid. Thus, only three phases‐FCCss, BCCss, and CaO‐coexist with liquids in the Bi2O3‐CaO system. However, several other phases are identified in the subsolidus region: Bi14Ca5O26, which is replaced by a Rhss phase and Bi2CaO4 at 745°± 5°C; Bi2CaO4, which decomposes to a FCCss phase and Bi6Ca4O13 at 776°± 3°C; Bi6Ca4O13, which is replaced by a BCCss phase and Bi2Ca2O5 at ∼878°± 3°C; and Bi2Ca2O5, which decomposes to a BCCss phase and CaO at 931°± 5°C.
Synthesis of Microcrystalline Hematite and Magnetite in Organic Solvents and Effect of a Small Amount of Water in the Solvents
Authors: Kominami Hiroshi , Onoue Sei‐ichi , Matsuo Kentarou , Kera Yoshiya
Published: January 2009

Microcrystalline magnetite (Fe3O4) particles having diameters of 7‐34 nm were synthesized by thermal treatment of iron(III) acetylacetonate in organic solvents at high temperatures (423‐573 K) and under autogenous pressures of the solvents. When the treatment was conducted in 1‐propanol containing a small amount of water (1‐3 vol%), nanosized hematite (α‐Fe2O3) crystallized, which then was reduced to magnetite after a prolonged reaction time, indicating that a small amount of water in 1‐propanol drastically changed the reaction mechanism for the formation of iron oxides.
Oxygen Vacancies in Pure Tetragonal Zirconia Powders: Dependence on the Presence of Chlorine during Processing
Authors: Karapetrova Evguenia , Platzer Roland , Gardner John A. , Torne Erwin , Sommers James A. , Evenson William E.
Published: January 2009

We have used several experimental methods to study how a large extrinsic oxygen vacancy density in pure tetragonal ZrO2 powders depends on details of how those powders are made. Samples were made from oxychloride and nitrate precursor solutions. We used perturbed angular correlation spectroscopy to determine in situ phase structure and the density of oxygen vacancies at 1200°C, XRD and SEM to determine the grain size and morphology of samples annealed at temperatures ranging from 200°–1200°C, and neutron activation analysis (NAA) to investigate purity of samples. NAA results showed that samples contain cation impurities at levels <<100 ppm. The XRD and SEM measurements showed that grains were nanometer‐size, had a broad distribution, and grew from ∼10 nm at 200°C to ∼1 μm at 1200°C. The most striking process dependence is on presence of chlorine during processing. The grain size and phase above 600°C, and both the morphology and the density of oxygen vacancies at 1200°C were strongly affected by presence of chlorine‐containing vapor during annealing. Samples processed in a chlorine‐free atmosphere had large well‐sintered grains and large (>500 ppm) oxygen vacancy concentrations at 1200°C, whereas samples processed in flowing H2O/HCl vapor had smaller grains, porous morphology, and small (<100 ppm) vacancy density. All samples were loose powders consisting of single grain particles at <1000°C and multiple‐grain particles at 1200°C.
Control of Phase and Pore Structure of Titania Powders Using HCl and NH4OH Catalysts
Authors: Song Ki Chang , Pratsinis Sotiris E.
Published: January 2009

Porous titania powders were prepared by hydrolysis of titanium tetraisopropoxide (TTIP) and were characterized at various calcination temperatures by nitrogen adsorption, X‐ray diffraction, and microscopy. The effect of HCl or NH4OH catalysts added during hydrolysis on the crystallinity and porosity of the titania powders was investigated. The HCl enhanced the phase transformations of the titania powders from amorphous to anatase as well as anatase to rutile, while NH4OH retarded both phase transformations. Titania powders calcined at 500°C showed bimodal pore size distributions: one was intra‐aggregated pores with average pore diameters of 3–6 nm and the other was interaggregated pores with average pore diameters of 35–50 nm. The average intra‐aggregated pore diameter was decreased with increasing HCl concentration, while it was increased with increasing NH4OH concentration.
Oxidation Behavior of Titanium Boride at Elevated Temperatures
Authors: Koh Young‐Hag , Lee Seung‐Yong , Kim Hyoun‐Ee
Published: January 2009

The oxidation behavior of dense TiB2 specimens was investigated. Hot‐pressed TiB2 with 2.5 wt% Si3N4 as a sintering aid was exposed to air at temperatures between 800° and 1200°C for up to 10 h. The TiB2 exhibited two distinct oxidation behaviors depending on the temperature. At temperatures below 1000°C, parabolic weight gains were observed as a result of the formation of TiO2(s) and B2O3(l) on the surface. The oxidation layer comprised two layers: an inner layer of crystalline TiO2 and an outer layer mainly composed of B2O3. When the oxidation temperatures were higher than 1000°C, gaseous B2O3 was formed along with crystalline TiO2 by the oxidation process. In this case, the surface was covered with large TiO2 grains imbedded in a highly textured small TiO2 matrix.
Effect of the Growth Treatment on Two‐Stage Nucleation Experiments
Authors: Davis Mark J.
Published: January 2009

Numerical simulations are presented that document the strong effect of a previously underappreciated portion of two‐stage thermal treatments used in the study of nucleation processes: the “heat‐up” process whereby samples are heated from “nucleation” conditions to “growth” conditions. The simulations indicate that two limiting regimes exist, dependent on (a) the cluster size distribution of as‐quenched glasses, (b) the temperatures used for nucleation and growth, and (c) the rates of heating and cooling: (1) all clusters larger than the critical size at growth conditions (n*gr) will grow to macroscopic size (the “standard” case); and (2) all clusters larger than the critical size at nucleation conditions (n*nuc) will grow to macroscopic size. In addition, cases in which the “effective critical size” (n*eff) is intermediate between n*gr and n*nuc can also occur. Cases in which n*eff < n*gr is manifested during nucleation experiments as an abrupt boost in crystal number density during the heat‐up from nucleation to growth conditions, as all clusters larger than n*eff are rapidly “flushed” past n*gr. For the system studied herein, this can lead to a 106‐fold increase in final number density within seconds to a few minutes. Finally, the importance of structural relaxation for this process is demonstrated by examining a case in which the nucleation temperature is below the nominal glass transition temperature.
Processing of Mullite–Aluminum Composites
Authors: Soundararajan Raji , Kuhn Gabe , Atisivan Raj , Bose Susmita , Bandyopadhyay Amit
Published: January 2009

Interconnected‐phase mullite–aluminum metal–ceramic composites were processed using the indirect fused‐deposition process. In this process, controlled‐porosity ceramic preforms were fabricated via the lost‐mold process. The molds were designed with computer aided design (CAD) software and fabricated using a fused‐deposition modeling (FDM) technique. Porous ceramic preforms were infiltrated with aluminum metal, via pressureless reactive metal infiltration, to form the mullite–aluminum composites. Both the macrostructures and the microstructures of the composites were controlled via CAD and FDM. During metal infiltration, the mullite phase transformed to α‐alumina, and an alumina–aluminum composite formed. This paper describes the mullite‐to‐alumina phase transformation during reactive metal infiltration of the porous preforms, as a function of processing variables.
Synthesis of Aluminum Oxide Platelets
Authors: Hill Richard F. , Danzer Robert , Paine Robert T.
Published: January 2009

Aqueous solutions of boehmite and hydrofluoric acid (HF) were used to prepare homogeneous mixtures of alumina and aluminum fluoride. Calcination at temperatures as low as 1000°C resulted in the formation of well‐defined hexagonal‐shaped α‐alumina platelets. Containment of the aluminum fluoride by covering the calcination crucible promoted crystal growth presumably by a reaction of continuous evaporation–condensation of aluminum fluoride. Hexagonal‐shaped platelet α‐alumina was observed with average diameters ranging from 7 to 33 μm. Large platelets with a narrow size distribution and average diameter of over 25 μm were prepared by controlling the initial concentration of HF and the calcination time, temperature, and atmosphere.
Thermal Shock Behavior of Iron‐Particle‐Toughened Alumina
Authors: Aldridge Matthew , Yeomans Julie A.
Published: January 2009

The thermal shock behavior of an alumina monolith and two alumina–iron ceramic‐matrix composites has been investigated by superimposing the measured KR‐curves of the materials onto the theoretically generated curves of the thermally induced stress intensity factor. Predictions of the critical‐temperature differentials and retained strengths after quenching are in good agreement with the experimental data. The inclusion of metallic particles into an alumina matrix improves the thermal shock resistance, although the increase in toughness is not solely responsible for this improvement. There is a decrease in thermal stress‐intensity factor that is generated for the composites; this decrease is due to a reduction in the Young's modulus and/or Biot modulus. However, the increased toughness for large crack lengths may offer increased damage resistance for severe thermal shock treatments.
Anatase‐to‐Rutile Transformation in Titania Powders
Authors: Gouma Pelagia I. , Mills Michael J.
Published: January 2009

Titania (TiO2) is an important electronic ceramic material for use in diverse applications such as gas sensors, catalysts, dielectrics, and ceramic membranes. TiO2 exists as several polymorphic phases, most commonly as rutile or anatase. This paper investigates the microstructural evolution of anatase‐based commercial TiO2 powders, with an average size of 100 nm, at high temperatures. These powders transform to the rutile structure at 1000°C. The characteristics of the anatase‐to‐rutile transformation have been studied using transmission electron microscopy analysis, and new information regarding the nature and mechanisms of this polymorphic reaction has been revealed.
Film Synthesis of Y3Al5O12 and Y3Fe5O12 by the Spray–Inductively Coupled Plasma Technique
Authors: Mizoguchi Yoshihito , Kagawa Masahiro , Syono Yasuhiko , Hirai Toshio
Published: January 2009

Thin films of yttrium aluminum garnet (YAG, Y3Al5O12) and yttrium iron garnet (YIG, Y3Fe5O12) were synthesized on single‐crystal Al2O3 substrates by a modification of spray pyrolysis using a high‐temperature inductively coupled plasma at atmospheric pressure (spray–ICP technique). Using this technique, films could be grown at faster rates (0.12 μm/min for YAG and 0.10 μm/min for YIG) than using chemical vapor deposition (0.005–0.008 μm/min for YAG) or sputtering (0.003–0.005 μm/min for YIG). The films were dense and revealed a preferred orientation of (211). The growth of YIG was accompanied by coprecipitation of α‐Fe2O3. The coprecipitation, however, could be largely suppressed by preliminary formation of a Y2O3 layer on the substrate.
Synthesis of Pb(Mg1/3Nb2/3)O3 in Excess Lead Oxide by Mechanical Activation
Authors: Xue Junmin , Wang John , Rao Tripti M.
Published: January 2009

Twenty hours of mechanical activation of mixed oxides at room temperature led to the formation of Pb(Mg1/3Nb2/3)O3 (PMN) in excess PbO. The crystallinity of the activation‐derived perovskite PMN phase was further established when the activated PMN–PbO phase mixture was subjected to calcination at 800°C. Pyrochlores, such as Pb3Nb4O13 and Pb2Nb2O7, were not observed as transitional phases on mechanical activation and subsequent calcination, although 50% excess PbO was deliberately added. The perovskite PMN phase was recovered by washing off excess PbO using acetic acid solution at room temperature. It was sintered to a relative density of 98.9% of theoretical at 1200°C for 1 h and the sintered PMN exhibited a dielectric constant of ∼14 000 at 100 Hz and a Curie temperature of −11°C.
Sol–Gel Preparation of BaTi4O9 and Ba2Ti9O20
Authors: Xu Yebin , Chen Xiang Ming , Wang Liangbin
Published: January 2009

BaTi4O9 and Ba2Ti9O20 precursors were prepared via a sol–gel method, using ethylenediaminetetraacetic acid as a chelating agent. The sol–gel precursors were heated at 700°–1200°C in air, and X‐ray diffractometry (XRD) was used to determine the phase transformations as a function of temperature. Single‐phase BaTi4O9 could not be obtained, even after heating the precursors at 1200°C for 2 h, whereas single‐phase Ba2Ti9O20 (as determined via XRD) was obtained at 1200°C for 2 h. Details of the synthesis and characterization of the resultant products have been given.
Phase Formation and Stability in Reactively Sputter Deposited Yttria‐Stabilized Zirconia Coatings
Authors: Ji Zhiqiang , Haynes J. Allen , Voelkl Edgar , Rigsbee J. Michael
Published: January 2009

Yttria‐stabilized zirconia (YSZ) coatings were produced by reactively cosputtering metallic zirconium and yttrium targets in an argon and oxygen plasma using a system with multiple magnetron sputtering sources. Coating crystal structure and phase stability, as functions of Y2O3 content, substrate bias, and annealing temperature, were investigated by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Results demonstrated that highly (111)‐oriented tetragonal and cubic zirconia structures were formed in 2 and 4.5 mol% Y2O3 coatings, respectively, when the coatings were grown with an applied substrate bias. Conversely, coatings deposited with no substrate bias had random tetragonal and cubic structures. XRD analysis of annealed coatings showed that the cubic zirconia in 4.5 mol% Y2O3 coatings exhibited structural stability at temperatures up to 1200°C. Transformation of the tetragonal to monoclinic phase occurred in 2 mol% Y2O3 coating during high‐temperature annealing, with the fraction of transformation dependent on bias potential and annealing temperature.
Permeability of Porous Ceramics Considering the Klinkenberg and Inertial Effects
Authors: Innocentini Murilo D. M. , Pandolfelli Victor C.
Published: January 2009

The literature reports that permeability constants differ in experiments conducted with gases or liquids. This behavior, known as the Klinkenberg effect, has been explained based on the gas‐slippage theory. We show here that inertial effects not considered by Darcy's law are the cause of variations in the gas permeability constant, kgas, with the mean pressure, Pm. The dependence of kgas and Pm on fluid flow is fully explained by the proposed model, based on Forchheimer's equation. The use of the gas‐slippage theory is unnecessary to explain variations in kgas obtained by Darcy's law.
Electromechanical Properties of a Ceramic d31‐Gradient Flextensional Actuator
Authors: Li Xiaoping , Vartuli James S. , Milius David L. , Aksay Ilhan A. , Shih Wan Y. , Shih Wei‐Heng
Published: January 2009

We examined the static axial displacement of a ceramic d31‐gradient flextensional transducer both experimentally and theoretically. Two lead zirconate titanate systems, (PZT)/PZT and PZT/ZnO, were studied. The PZT/PZT transducers consisted of two PZT layers of different d31 coefficients. The PZT/ZnO transducers consisted of a PZT and a ZnO layer. The PZT/PZT transducers were of an inner‐type dome structure. The PZT/ZnO transducers were either flat, or had an inner‐ or outer‐type dome structure by varying the thickness ratio between the two layers or the Sb2O3 content in the ZnO layer. An inner (outer)‐type transducer has the large‐d31 layer on the inside (outside) of the dome structure. For the PZT/PZT transducers, the axial displacement varied with the thickness ratio and reached a maximum when the two layers had similar thickness, in agreement with the calculations. With a conductive nonpiezoelectric layer, the PZT/ZnO transducers had higher axial displacements, which varied with the thickness ratio and the Sb2O3 content, than the PZT/PZT transducers. With 6 wt% Sb2O3, the transducers were flat and the measured displacements at various thickness ratios were similar to the calculated values. With 4 wt% Sb2O3, the transducers were of an outer type. The measured axial displacements were about twice the calculated values, suggesting an enhanced d31 value because of the tensile bending stress in the PZT layer. The scaled axial displacements of the PZT/ZnO transducers with 4 wt% Sb2O3 were comparable to that of the Rainbow transducers. With 8 wt% Sb2O3, the displacements of transducers with thin PZT layers (≤0.3 mm) were lower than the calculated values because of increased conductivity in the PZT layer.
Cation Effects on Anion Distributions in Aluminophosphate Glasses
Authors: Metwalli EzzEldin , Brow Richard K. , Stover Frederick S.
Published: January 2009

Alkali aluminophosphate glasses, including those in the system xAl2O3·(1−x)CsPO3 (0 ≤x≤ 0.25), were examined by high‐performance liquid chromatography (HPLC), infrared (IR), and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies. Phosphate anions become progressively shorter with the addition of alumina to a metaphosphate glass. Al3+ ions are initially incorporated into the structure in octahedral sites, but the average Al coordination number (CN) decreases with increasing alumina content and tetrahedral species are the preferred moiety when [O]/[P] > 3.5. Al[4] sites appear to be associated with monophosphate (Q0) anions. The role of modifier size on aluminophosphate structure is investigated. At low alumina content (<15 mol%), the disproportionation of pyrophosphate anions into triphosphate and orthophosphate anions is responsible for the lower average Al CN of cesium aluminophosphate glasses compared with sodium aluminophosphate glasses.
Creep Viscosity and Stress Relaxation of Gel‐Derived Silicon Oxycarbide Glasses
Authors: Rouxel Tanguy , Soraru Gian‐Domenico , Vicens Jean
Published: January 2009

The temperature dependence of the viscosity and stress‐relaxation kinetics of sol–gel‐derived SiOC glasses that contain up to 14 at.% carbon have been characterized in the temperature range of 1000°–1400°C. The viscosity, as determined from relaxation experiments, is in good agreement with the creep viscosity and is typically two orders of magnitude higher than the viscosity of vitreous silica. However, materials suffer from partial crystallization at >1150°C, and the precipitation of β‐SiC nanocrystals induces a flow‐hardening behavior and results in a dynamic increase in viscosity, especially at >1200°C and for glasses with a high carbon content.
Characterization of Liquid Exsolved by Remelting Reaction of Belite
Authors: Fukuda Koichiro , Takeda Ayari , Yamaguchi Akira , Hashimoto Shinobu , Yoshida Hideto
Published: January 2009

We examined the chemistry and structure of the liquid that was exsolved by the remelting reaction of belite. Electron probe microanalysis revealed that the liquid concentrated the impurity components (e.g., Na2O, K2O, Al2O3, and Fe2O3) of the parent belite. Micro‐Raman spectroscopy showed the similarity of the spectra of the exsolved liquid and amorphous calcium aluminoferrite solid solution. The transition from the crystalline to the amorphous state of the solid solution was induced by increasing the excitation laser power. Accordingly, the liquid at ambient temperature was most likely in a glassy state. The chemical composition of the liquid, deduced from the above experiments, was ∼81 mass% Ca2AlFeO5 and ∼19 mass% Ca2SiO4. The alkalies, which have never been detectable in crystalline calcium aluminoferrite, were probably necessary for the vitrification of the liquid.
Nanoindentation of a Polymer‐Derived Amorphous Silicon Carbonitride Ceramic
Authors: Galusek Dušan , Riley Frank L. , Riedel Ralf
Published: January 2009

Nanoindentation has revealed significant scatter of the microscale hardness and elastic modulus of an amorphous SiCN ceramic, because of structural inhomogeneities (nanopores and clusters of free carbon within the material). As a consequence of the common feature, an amorphous nature, SiCN, in regard to its mechanical properties, resembles SiO2glass more than SiC or Si3N4. However, because of the stronger Si—C and Si—N covalent bonding, SiCN is harder and stiffer than SiO2. The mean hardness—13 ± 2 GPa, measured at a load of 250 mN for SiCN—is approximately half that of polycrystalline Si3N4(24.9 ± 0.6 GPa) but higher than that of SiO2glass (8.9 ± 0.04 GPa). The elastic modulus of the SiCN, measured at a load of 250 mN, is 121 ± 10 GPa.
Thermal Decomposition of Titanium Alkoxide and Silicate Ester in Organic Solvent: A New Method for Synthesizing Large‐Surface‐Area, Silica‐Modified Titanium(IV) Oxide of High Thermal Stability
Authors: Kominami Hiroshi , Kohno Masaaki , Matsunaga Yukino , Kera Yoshiya
Published: January 2009

Silica‐modified titanium oxide (S‐TiO2) powders that have an anatase structure were synthesized via the thermal decomposition of mixtures of titanium(IV) isopropoxide (TIP) and tetramethyl orthosilicate (TMOS) in toluene at 300°C. These S‐TiO2 materials had high rutile‐transformation temperatures and maintained large surface areas at elevated temperatures (550°–1000°C). For example, the product that was prepared from a 9:1 TIP:TMOS mixture transformed to rutile at ∼1100°C and possessed a surface area of 160 m2/g, even after calcination at 800°C for 1 h.
Estimation of the Effectived31Coefficients of the Piezoelectric Layer in Rainbow Actuators
Authors: Schwartz Robert W. , Cross L. Eric , Wang Qing Ming
Published: January 2009

We have analyzed the performance of Rainbow (reduced and internally biased oxide wafer) actuators by assuming that the key difference between these devices and unimorph actuators is the presence of internal stress that alters the extrinsic (domain switching) contribution to electromechanical response, and thus, the effectived31coefficient of the piezoelectric layer. Based on this assumption, we calculated thed31coefficient as a function of device geometry and electric field and found that the coefficients ranged from approximately −300 to −600 pm/V. The highestd31value was obtained for a Rainbow actuator that was fabricated by reducing 1/3 of the piezoelectric layer; other studies indicated that this device possessed the highest tensile stress in the surface region of the piezoelectric. We observed that geometric effects on calculatedd31coefficients were as significant as voltage effects. The analytical approach utilized also permitted estimation of the relative contributions of mechanical and stress effects to the performance of these devices, which were determined to be dependent on field and geometry. Although the estimatedd31coefficient for certain geometries is twice the typical low field value, it must be remembered that this value represents an “average” value for the entire piezoelectric layer, which is under a stress gradient; i.e., the lower region of the piezoelectric is in lateral compression, while the upper region is in lateral tension. This suggests that the true electromechanical coefficients of the lead zirconate titanate composition utilized in these devices would display an even broader range ofd31values, ifd31was characterized as a function of uniform lateral stress.
Thermal Expansion Behavior of Titanium‐Doped La(Sr)CrO3 Solid Oxide Fuel Cell Interconnects
Authors: Mori Masashi , Hiei Yoshiko
Published: January 2009

La0.8Sr0.2Cr0.9Ti0.1O3 perovskite has been designed as an interconnect material in high‐temperature solid oxide fuel cells (SOFCs) because of its thermal expansion compatibility in both oxidizing and reducing atmospheres. La0.8Sr0.2Cr0.9Ti0.1O3 shows a single phase with a hexagonal unit cell of a= 5.459(1) Å, c= 13.507(2) Å, Z= 6 and a space group of R‐3C. Average linear thermal expansion coefficients of this material in the temperature range from 50° to 1000°C were 10.4 × 10−6/°C in air, 10.5 × 10−6/°C under a He–H2 atmosphere (oxygen partial pressure of 4 × 10−15 atm at 1000°C), and 10.9 × 10−6/°C in a H2 atmosphere (oxygen partial pressure of 4 × 10−19 atm at 1000°C). La0.8Sr0.2Cr0.9Ti0.1O3 perovskite with a linear thermal expansion in both oxidizing and reducing environments is a promising candidate material for an SOFC interconnect. However, there still remains an air‐sintering problem to be solved in using this material as an SOFC interconnect.