bluuebunny/crossref_metadata_2025 huggingface dataset:
Satisfaction with Surgery Outcomes and the Decision Process in a Population‐Based Sample of Women with Breast Cancer
Authors: Lantz Paula M. , Janz Nancy K. , Fagerlin Angela , Schwartz Kendra , Liu Lihua , Lakhani Indu , Salem Barbara , Katz Steven J.
Published: May 2005

Objective. To better understand medical decision making in the context of “preference sensitive care,” we investigated factors associated with breast cancer patients' satisfaction with the type of surgery received and with the decision process.

Data Sources/Data Collection. For a population‐based sample of recently diagnosed breast cancer patients in the Detroit and Los Angeles metropolitan areas (N=1,633), demographic and clinical data were obtained from the Surveillance, Epidemiology, and End Results tumor registry, and self‐reported psychosocial and satisfaction data were obtained through a mailed survey (78.4 percent response rate).

Study Design. Cross‐sectional design in which multivariable logistic regression was used to identify sociodemographic and clinical factors associated with three satisfaction measures: low satisfaction with surgery type, low satisfaction with the decision process, and decision regret.

Principal Findings. Overall, there were high levels of satisfaction with both surgery and the decision process, and low rates of decision regret. Ethnic minority women and those with low incomes were more likely to have low satisfaction or decision regret. In addition, the match between patient preferences regarding decision involvement and their actual level of involvement was a strong indicator of satisfaction and decision regret/ambivalence. While having less involvement than preferred was a significant indicator of low satisfaction and regret, having more involvement than preferred was also a risk factor. Women who received mastectomy without reconstruction were more likely to report low satisfaction with surgery (odds ratio [OR]=1.54, p<.05), low satisfaction with the process (OR=1.37, p<.05), and decision regret (OR=1.55, p<.05) compared with those receiving breast conserving surgery (BCS). An additional finding was that as patients' level of involvement in the decision process increased, the rate of mastectomy also increased (p<.001).

Conclusions. A significant proportion of breast cancer patients experience a decision process that matches their preferences for participation, and report satisfaction with both the process and the outcome. However, women who report more involvement in the decision process are significantly less likely to receive a lumpectomy. Thus, increasing patient involvement in the decision process will not necessarily increase use of BCS or lead to greater satisfaction. The most salient aspect for satisfaction with the decision making process is the match between patients' preferences and experiences regarding participation.
Health Services for Women in Outpatient Substance Abuse Treatment
Authors: Campbell Cynthia I. , Alexander Jeffrey A.
Published: May 2005

Objective. To evaluate how a sample of outpatient substance abuse treatment units respond to organizational and environmental influences by adopting and implementing treatment services for women.

Data Sources. The National Drug Abuse Treatment System Survey from 1995 and 2000, a national survey of outpatient substance abuse treatment units.

Study Design. Health services for women are the dependent variables. The predictors include organizational and environmental factors that represent resource dependence and institutional pressures for the treatment unit. Logistic regression and Heckman selection models were used to test hypotheses.

Data Collection. Program directors and clinical supervisors at each treatment unit were interviewed by telephone in 1995 and 2000.

Principal Findings. Units that depended on specific funding for women's programs and that depended on government funds were more likely to adopt, but not necessarily implement, women's services. Methadone units and units that train more staff to work with women were more likely to adopt as well as implement women's services. Private not‐for‐profit units were more likely to adopt some services, while for‐profit units were less so. However, in general, neither for‐profit nor not‐for‐profit units significantly implemented services. There was evidence that the odds of adopting services were greater in 2000 than 1995 for two services, but were otherwise stable.

Conclusions. There is considerable variation in the adoption and implementation of women's services. In addition, not all adopted services were significantly implemented, which could reflect limited organizational resources and/or conflicting expectations. This also suggests that referral mechanisms to these services, and therefore access, may not be adequate. Government funds and specific funds for women's programs are important resources for the provision of these services. Women's services appear more available in methadone units, suggesting that regulation has been influential and that the recent methadone accreditation system should be evaluated. Staff training may be one strategy to encourage implementation of these services. For the most part, the adoption of services for women did not change between 1995 and 2000.
Do Seniors Understand Their Risk of Moving to a Nursing Home?
Authors: Taylor Donald H. , Osterman Jan , Will Acuff S. , Østbye Truls
Published: May 2005

Objective. To determine whether seniors understand their risk of moving to a nursing home.

Data Sources. We used longitudinal data from the Asset and Health Dynamics Among the Oldest Old (AHEAD) database. AHEAD is a nationally representative survey (n=8,203) of community dwellers aged 70+ years and their spouses.

Study Design. We followed respondents for 5 years from the date of the first interview fielded in 1993. Our primary dependent variable was whether respondents moved to a nursing home within 5 years of baseline; self‐assessed probability of moving to a nursing home within 5 years, also assessed at baseline, was the primary explanatory variable.

Principal Findings. We found that seniors who believed they were more likely to move to a nursing home within 5 years were indeed more likely to do so, and that most elders overestimated their likelihood of moving to a nursing home.

Conclusions. Low rates of private long‐term care insurance are not plausibly a result of seniors underestimating their personal risk of moving to a nursing home; such an assumption is inherent in many strategies to plan for the future long‐term care needs of the baby boom generation.
Not of One Mind: Mental Models of Clinical Practice Guidelines in the Veterans Health Administration
Authors: Hysong Sylvia J. , Best Richard G. , Pugh Jacqueline A. , Moore Frank I.
Published: May 2005

Objective.The purpose of this paper is to present differences in mental models of clinical practice guidelines (CPGs) among 15 Veterans Health Administration (VHA) facilities throughout the United States.

Data Sources.Two hundred and forty‐four employees from 15 different VHA facilities across four service networks around the country were invited to participate. Participants were selected from different levels throughout each service setting from primary care personnel to facility leadership.

Study Design.This qualitative study used purposive sampling, a semistructured interview process for data collection, and grounded theory techniques for analysis.

Data Collection.A semistructured interview was used to collect information on participants' mental models of CPGs, as well as implementation strategies and barriers in their facility.

Findings.Analysis of these interviews using grounded theory techniques indicated that there was wide variability in employees' mental models of CPGs. Findings also indicated that high‐performing facilities exhibited both (a) a clear, focused shared mental model of guidelines and (b) a tendency to use performance feedback as a learning opportunity, thus suggesting that a shared mental model is a necessary but not sufficient step toward successful guideline implementation.

Conclusions.We conclude that a clear shared mental model of guidelines, in combination with a learning orientation toward feedback are important components for successful guideline implementation and improved quality of care.
Imputation of SF‐12 Health Scores for Respondents with Partially Missing Data
Authors: Liu Honghu , Hays Ron D. , Adams John L. , Chen Wen‐Pin , Tisnado Diana , Mangione Carol M. , Damberg Cheryl L. , Kahn Katherine L.
Published: May 2005

Objective. To create an efficient imputation algorithm for imputing the SF‐12 physical component summary (PCS) and mental component summary (MCS) scores when patients have one to eleven SF‐12 items missing.

Study Setting. Primary data collection was performed between 1996 and 1998.

Study Design. Multi‐pattern regression was conducted to impute the scores using only available SF‐12 items (simple model), and then supplemented by demographics, smoking status and comorbidity (enhanced model) to increase the accuracy. A cut point of missing SF‐12 items was determined for using the simple or the enhanced model. The algorithm was validated through simulation.

Data Collection. Thirty‐thousand‐three‐hundred and eight patients from 63 physician groups were surveyed for a quality of care study in 1996, which collected the SF‐12 and other information. The patients were classified as “chronic” patients if they reported that they had diabetes, heart disease, asthma/chronic obstructive pulmonary disease, or low back pain. A follow‐up survey was conducted in 1998.

Principal Findings. Thirty‐one percent of the patients missed at least one SF‐12 item. Means of variance of prediction and standard errors of the mean imputed scores increased with the number of missing SF‐12 items. Correlations between the observed and the imputed scores derived from the enhanced models were consistently higher than those derived from the simple model and the increments were significant for patients with ≥6 missing SF‐12 items (p<.03).

Conclusion. Missing SF‐12 items are prevalent and lead to reduced analytical power. Regression‐based multi‐pattern imputation using the available SF‐12 items is efficient and can produce good estimates of the scores. The enhancement from the additional patient information can significantly improve the accuracy of the imputed scores for patients with ≥6 items missing, leading to estimated scores that are as accurate as that of patients with <6 missing items.
Habitat Restoration as a Means of Controlling Non‐Native Fish in a Mojave Desert Oasis
Authors: Scoppettone G. Gary , Rissler Peter H. , Gourley Chad , Martinez Cynthia
Published: May 2005

Non‐native fish generally cause native fish decline, and once non‐natives are established, control or elimination is usually problematic. Because non‐native fish colonization has been greatest in anthropogenically altered habitats, restoring habitat similar to predisturbance conditions may offer a viable means of non‐native fish control. In this investigation we identified habitats favoring native over non‐native fish in a Mojave Desert oasis (Ash Meadows) and used this information to restore one of its major warm water spring systems (Kings Pool Spring). Prior to restoration, native fishes predominated in warm water (25–32°C) stream and spring‐pool habitat, whereas non‐natives predominated in cool water (≤23°C) spring‐pool and marsh/slack water habitat. Native Amargosa pupfish (Cyprinodon nevadensis) and Ash Meadows speckled dace (Rhinichthys osculus nevadensis) inhabited significantly faster mean water column velocities (MWCV) and greater total depth (TD) than non‐native Sailfin molly (Poecilia latipinna) and Mosquitofish (Gambusia affinis) in warm water stream habitat, and Ash Meadows speckled dace inhabited significantly faster water than non‐natives in cool water stream habitat. Modification of the outflow of Kings Pool Spring from marsh to warm water stream, with MWCV, TD, and temperature favoring native fish, changed the fish composition from predominantly non‐native Sailfin molly and Mosquitofish to predominantly Ash Meadows pupfish. This result supports the hypothesis that restoring spring systems to a semblance of predisturbance conditions would promote recolonization of native fishes and deter non‐native fish invasion and proliferation.
The Restoration of Plant–Pollinator Interactions in Hay Meadows
Authors: Forup Mikael Lytzau , Memmott Jane
Published: May 2005

Whether restoration programs successfully reinstate ecological interactions remains a contentious and largely untested issue. We investigated plant and pollinator interactions on two old and two restored hay meadows, with the aim of evaluating if quantitative patterns of insect visitation and pollen transport were comparable among old and restored meadows. In terms of structural diversity, few species of plants and insects were shared among the webs. In all four meadows, Diptera and Hymenoptera dominated the visitor community in terms of both species richness and abundance. Coleoptera, Hemiptera, and Lepidoptera comprised the remainder of the flower visitors. No significant difference was found between restored and old sites in plant or insect species richness or in plant and insect abundance. In terms of function, the meadows appeared more similar, although a slightly higher proportion of the potential links between plants and insects was realized for old meadows. No difference was found in the proportion of plant species visited, and visited plant species were generalized, with all having more than a single species of insect visitor. We also sampled approximately 400,000 pollen grains from the flower‐visiting insects. There were no differences between old and restored sites in the amount of pollen being transported or in the average number of pollen grains per insect. At both types of meadows, Hymenoptera carried most pollen, followed by Diptera. Again, generalization was the norm, with all plants having more than a single species of pollen carrier. No difference was observed in the connectance of pollen transport webs between old and restored sites. Overall, although the four meadows showed considerable structural variation, they showed similarity with regard to the functional processes we studied. Because structural variation is expected among localities, we conclude that the two restoration projects have been successful.
Avian Use of Restoration Plantings along a Creek Linking Rainforest Patches on the Atherton Tablelands, North Queensland
Authors: Jansen Amy
Published: May 2005

Rainforest fragmentation and creek degradation are major problems on the Atherton Tablelands in North Queensland. Lake Barrine and Wooroonooran National Parks are separated by a 1.5‐km length of Toohey's Creek which has been cleared except for small remnant rainforest patches. The creek has been fenced and replanted to create a corridor between the two national parks. The aim of this study was to monitor the success of the corridor in providing habitat for rainforest birds. Avian communities were monitored in the corridor and in adjacent rainforest sites using point counts over the period of reestablishment of a continuous rainforest canopy. In terms of bird community composition, within 3 years of planting, the replanted sites were on a trajectory toward the rainforest sites. Although specialist rainforest species were not yet found in the plantings, after 3 years those species which mainly inhabit rainforest but also utilize edges and riparian strips were found in similar numbers in the plantings and in the small remnant patches along the corridor. Frugivorous species were quite abundant even in the youngest plantings. Thus, replanting of rainforest trees along Toohey's Creek has begun to provide habitat for some rainforest birds. It also shows good potential to act as a corridor to connect the previously isolated patches of rainforest for these species and to develop in habitat complexity as the frugivorous birds bring in rainforest plant species from nearby areas.
Catchment Liming to Restore Degraded, Acidified Heathlands and Moorland Pools
Authors: Dorland Edu , Van Den Berg Leon J. L. , Brouwer Emiel , Roelofs Jan G. M. , Bobbink Roland
Published: May 2005

Current restoration measures of degraded, acidified heathland ecosystems have not always been successful in the Netherlands. Positive effects of a restored hydrology are often counteracted by acidification of the soil and the local groundwater system. Liming of the heathlands in the catchment of moorland pools might contribute to the restoration of both habitats. Experimental catchment liming was carried out in two degraded Dutch heathlands, with doses varying between 2 and 6 tons/ha. Catchment liming resulted in increased pH and base cation concentrations in the highest elevated limed parts, as well as in the lower situated, nonlimed heath areas and moorland pools. Generally, catchment liming created suitable conditions for the return of heathland target species, and the positive effects lasted for at least 6 years. The response of the heathland vegetation to the liming has, however, been slow because only a small number of endangered plant species increased in abundance. In contrast, four Red List soft‐water macrophytes strongly increased in abundance in the moorland pool. Our results show that, even with the slow return of Red List plant species, catchment liming can be a successful management tool for the restoration of the acidified heathland landscape.
Invading Monotypic Stands of Phalaris arundinacea: A Test of Fire, Herbicide, and Woody and Herbaceous Native Plant Groups
Authors: Foster Richard D. , Wetzel Paul R.
Published: May 2005

Phalaris arundinacea L. is an aggressive species that can dominate wetlands by producing monotypic stands that suppress native vegetation. In this study invasion windows were created for native species in monotypic stands of P. arundinacea with either fire or herbicide. Three native species groups, herbaceous plants, herbaceous seeds, and woody shrubs, were planted into plots burned or treated with herbicide in the early spring. Fire did not create an effective invasion window for native species; there was no difference in P. arundinacea root and shoot biomass or cover between burned and control plots (p≥ 0.998). Herbicide treatment created an invasion window for native species by reducing P. arundinacea root and shoot biomass for two growing seasons, but that invasion window was fast closing by the end of the second growing season because P. arundinacea shoot biomass had nearly reached the shoot biomass levels in the control plots (p= 0.053). Transplant mortality, frost, and animal herbivory prevented the herbaceous species and woody seedlings from becoming fully established in the plots treated with herbicide during the first year of the experiment. Transplanted monocots had a greater survival than dicots. By the second growing season the herbaceous group had the greatest mean areal cover (5%), compared to the woody seedlings (3%) and seed group (0%). Long‐term monitoring of the plots will determine whether the herbaceous transplants will compete effectively with P. arundinacea and whether the woody species will survive, shade the P. arundinacea, and accelerate forest succession.
An Ecologically Based Approach to Identifying Restoration Priorities in an Acid‐Impacted Watershed
Authors: Petty J. Todd , Thorne David
Published: May 2005

The extent of impairment to some Appalachian watersheds from acid precipitation is so extreme that watershed scale analytical tools are needed to help guide cost‐effective management decisions. The objective of this study was to develop a measure of the functional value of streams as potential areas for juvenile Brook trout recruitment. This measure, which we term “weighted potential recruitment area” (WPRA), is a function of the expected Brook trout spawning intensity and juvenile survivorship. Estimates of WPRA for each stream segment were then used to identify restoration priorities and optimal restoration programs in the upper Shavers Fork watershed in West Virginia, U.S.A. Using this approach, we determined that the watershed has lost nearly 80% of its historic juvenile recruitment potential as a result of acid precipitation. We also determined that of the 145 stream segments in the watershed, eight critical stream segments account for nearly 20% of the loss. The costs and ecological benefits of a series of five alternative restoration programs were then assessed using an ArcGIS model (Environmental Systems Research Institute, Redlands, CA, U.S.A.). This approach identified two “optimal” alternatives: (1) a low‐cost, moderate‐benefit approach that would use existing rail access to treat acidification in three critical headwater locations and (2) a high‐cost, high‐benefit approach that would use aerial limestone application to treat numerous acidic tributaries near their source. The measure of stream ecological value that we developed was effective in identifying critical restoration priorities and optimal restoration strategies in this watershed. A similar procedure could be used to guide watershed restoration decisions throughout the Appalachian region.
Restoration of Arthropod Assemblages in a Spartina Salt Marsh following Removal of the Invasive Plant Phragmites australis
Authors: Gratton Claudio , Denno Robert F.
Published: May 2005

Invasive plants are one of the most serious threats to native species assemblages and have been responsible for the degradation of natural habitats worldwide. As a result, removal of invasive species and reestablishment of natural vegetation have been attempted in order to restore biodiversity and ecosystem function. This study examined how native arthropod assemblages, an abundant and functionally important group of organisms in many ecosystems, are affected by the incursion of the invasive wetland plant Phragmites australis and if the restoration of the native vegetation in brackish Spartina alterniflora marshes results in the reestablishment of the arthropod community. The invasion of Phragmites into a coastal Spartina marsh in southern New Jersey seriously altered arthropod assemblages and trophic structure by changing the abundance of trophic groups (detritivores, herbivores, carnivores) and their taxonomic composition. Herbivore assemblages shifted from the dominance of external free‐living specialists (e.g., planthoppers) in Spartina to concealed feeders in Phragmites (stem‐feeding cecidomyiids). Moreover, free‐living arthropods in Phragmites became dominated by detritivores such as Collembola and chironomids. The dominant marsh spiders, web‐building linyphiids, were significantly reduced in Phragmites habitats, likely caused by differences in the physical environment of the invaded habitats (e.g., lower stem densities). Thus, trophic structure of arthropod assemblages in Phragmites, as seen in the large shifts in feeding guilds, was significantly different from that in Spartina. Removal of Phragmites with the herbicide glyphosate resulted in the rapid return of Spartina (≤5 yrs). Moreover, return of the dominant vegetation was accompanied by the recovery of most original habitat characteristics (e.g., live and dead plant biomass, water flow rate). The arthropod assemblage associated with Spartina also quickly returned to its preinvasion state and was not distinguishable from that in uninvaded Spartina reference sites. This study provides evidence that the reestablishment of native vegetation in areas previously altered by an invasive plant can result in the rapid recovery of the native arthropod assemblage associated with the restored habitat.
Experimental Restoration of an Indigenous Hawaiian Grassland after Invasion by Buffel Grass (Cenchrus ciliaris)
Authors: Daehler Curtis C. , Goergen Erin M.
Published: May 2005

Introduced grasses have displaced Hawaiian Pili grass (Heteropogon contortus) in most dry, leeward habitats of the Hawaiian Islands. The purpose of this study was to assess the feasibility of restoring an indigenous Heteropogon grassland at the Puukohola Heiau National Historic Site, where introduced Buffel grass (Cenchrus ciliaris) is now dominant. Heteropogon seeds (50 seedlings/m2) were added to replicate plots within a Cenchrus grassland. Some plots were subjected to one‐time herbicide or hand‐pulling treatments to remove established Cenchrus. Because Hawaiians historically used fire to promote Heteropogon grasslands, the plots were burned biennially. Plots were also subjected to two levels of water supplementation. Heteropogon establishment was monitored over 2 and 4 years in the higher‐ and lower‐water plots, respectively. In treatments containing established Cenchrus, Heteropogon establishment was consistently poor (<10% cover). But in the burned plots where established Cenchrus had been removed, as many as 31 Heteropogon seedlings per square meter were recorded, and Heteropogon became the dominant cover, averaging 34% absolute cover (81% relative cover) after 4 years in the lower‐water plot and 34% absolute cover (60% relative cover) after 2 years in the higher‐water plot. Few Cenchrus grass seedlings survived, possibly due to insufficient water. Water supplementation promoted growth of other alien grasses from the seed bank (Digitaria insularis and Eragrostis spp.); however, these grasses quickly declined after supplemental watering was terminated. Although initial suppression of Cenchrus was required, Heteropogon expanded quickly when seeds and fire were reintroduced, demonstrating that a Heteropogon‐dominated grassland can be reestablished in 2–4 years.
Diminishing Spatial Heterogeneity in Soil Organic Matter across a Prairie Restoration Chronosequence
Authors: Lane Diana R. , BassiriRad Hormoz
Published: May 2005

Habitat restoration resulting in changes in plant community composition or species dominance can affect the spatial pattern and variability of soil nutrients. Questions about how these changes in soil spatial heterogeneity develop over time at restoration sites, however, remain unaddressed. In this study, a geostatistical approach was used to quantify changes over time in the spatial heterogeneity of soil organic matter (SOM) across a 26‐year chronosequence of tallgrass prairie restoration sites at FermiLab, outside of Chicago, Illinois. We used total soil N and C as an index of the quantity of SOM. We also examined changes in C:N ratio, which can influence the turnover of SOM. Specifically, the spatial structure of total N, total C, and C:N ratio in the top 10 cm of soil was quantified at a macroscale (minimum spacing of 1.5 m) and a microscale (minimum spacing of 0.2 m). The magnitude of spatial heterogeneity (MSH) was characterized as the proportion of total sample variation explained by spatially structured variation. At the macroscale, the MSH for total N decreased with time since restoration (r2= 0.99, p < 0.001). The decrease in spatial heterogeneity over time corresponded with a significant increase in the dominance of the C4 grasses. At the microscale, there was significant spatial structure for total N at the 4‐year‐old, 16‐year‐old, and 26‐year‐old sites, and significant spatial structure for total C at the 16‐year‐old and 26‐year‐old sites. These results suggest that an increase in dominance of C4 grasses across the chronosequence is homogenizing organic matter variability at the field scale while creating fine‐scale patterns associated with the spacing of vegetation. Areas of higher soil moisture were associated with higher soil N and C at the two oldest restoration sites and at the native prairie site, potentially suggesting patches of increased belowground productivity in areas of higher soil moisture. This study is one of the first to report significant changes over time in the spatial structure of organic matter in response to successional changes initiated by restoration.
The Implied Longevity Yield: A Note on Developing an Index for Life Annuities
Authors: Milevsky Moshe A.
Published: May 2005

Abstract

I develop an index for tracking the dynamic behavior of life (pension) annuity payouts over time, based on the concept of self‐annuitization. Our implied longevity yield (ILY) value is defined equal to the internal rate of return (IRR) over a fixed deferral period that an individual would have to earn on their investable wealth if they decided to self‐annuitize using a systematic withdrawal plan. A larger ILY number indicates a greater relative benefit from immediate annuitization. I use age 65—with a 10‐year period certain—compared against the same annuity at age 75 as the standard benchmark for the index, and calibrate to a comprehensive time series of weekly (Canadian) life annuity quotes from 2000 through 2004. I find that during this period the ILY varied from 5.45 percent to 6.90 percent for males and from 5.00 percent to 6.42 percent for females and was highly correlated with a duration‐weighted average yield of 10‐year and long‐term Government of Canada bonds. I believe our ILY metric can help promote and explain the benefits of acquiring lifetime payout annuities by translating the abstract‐sounding longevity insurance into more concrete and measurable financial rates of return.
Fracture Energies of Tape‐Cast Silicon Nitride with β‐Si3N4 Seed Addition
Authors: Zeng Yu‐Ping , Yang Jian‐Feng , Kondo Naoki , Ohji Tatsuki , Kita Hideki , Kanzaki Shuzo
Published: May 2005

The fracture energies of the tape‐cast silicon nitride with and without 3 wt% rod‐like β‐Si3N4 seed addition were investigated by a chevron‐notched‐beam technique. The material was doped with Lu2O3–SiO2 as sintering additives for giving rigid grain boundaries and good heat resistance. The seeded and tape‐cast silicon nitride has anisotropic microstructure, where the fibrous grains grown from seeds were preferentially aligned parallel to the casting direction. When a stress was applied parallel to the fibrous grain alignment direction, the strength measured at 1500°C was 738 MPa, which was almost the same as room temperature strength 739 MPa. The fracture energy of the tape‐cast Si3N4 without seed addition was 109 and 454 J/m2 at room temperature and 1500°C, respectively. On the contrary, the fracture energy of the seeded and tape‐cast Si3N4 was 301 and 781 J/m2 at room temperature and 1500°C, respectively, when a stress was applied parallel to the fibrous gain alignment. The large fracture energies were attributable primarily to the unidirectional alignment fibrous Si3N4 grains.
Mechanical and Magnetic Properties of Novel Yttria‐Stabilized Tetragonal Zirconia/Ni Nanocomposite Prepared by the Modified Internal Reduction Method
Authors: Kondo Hiroki , Sekino Tohru , Tanaka Norihito , Nakayama Tadachika , Kusunose Takafumi , Niihara Koichi
Published: May 2005

Dense ceramic/metal nanocomposite has been fabricated by internal reduction method, which includes a two‐step process: sintering of ceramic–metal oxide solid solution and subsequent heat treatment in a reducing atmosphere to precipitate metal nanoparticles. This novel technique has been applied to yttria‐stabilized tetragonal zirconia (Y‐TZP) and nickel oxide (NiO) system to fabricate Y‐TZP/Ni nanocomposite. Dense Y‐TZP and 0.3 mol% NiO solid solution ceramic was successively prepared by the pressureless sintering, and Y‐TZP/Ni was fabricated by the internal reduction treatment. The obtained Y‐TZP/Ni nanocomposite possessed characteristic intragranular nanostructure with nano‐sized metallic Ni particles of around 20 nm. Fracture toughness of both the solid solution and nanocomposite was remarkably improved because of the solid solution of NiO into Y‐TZP and resultant destabilization of the tetragonal phase, and the Y‐TZP/Ni nanocomposite was still destabilized by the remaining nickel solution after the reduction. The nanocomposite exhibited ferromagnetism, while the Y‐TZP–NiO solid solution had diamagnetic nature. Comparison of saturation magnetization values revealed that 39.5 at.% of introduced nickel was reduced to metallic nanoparticle, proving the existence of residual NiO solute in zirconia that contributed to higher toughness value than the monolithic Y‐TZP. It is concluded that the introduced internal reduction method is a suitable process to achieve multifunctional ZrO2/Ni nanocomposite with high toughness and coexistent magnetic characteristic.
Dielectric Properties and Microstructures of Ba(Ti,Zr)O3 Multilayer Ceramic Capacitors with Ni Electrodes
Authors: Feng Qiquan , McConville Caspar J. , Edwards Doreen D.
Published: May 2005

The microstructures and dielectric properties of multilayer ceramic capacitors based on reoxidized Ba(Ti0.88,Zr0.12)O3 (BTZ) materials with Ni electrodes were studied using transmission electron microscopy. Dielectric measurements showed that the BTZ materials exhibited frequency relaxation effects. Although X‐ray diffraction showed a single pseudocubic phase, split and elongated electron diffraction spots were observed using selected area diffraction (SAD). There were no super‐lattice diffraction spots in the SAD pattern. The microstructures of BTZ dielectric materials were observed at dynamical diffraction conditions, and multidomain structures coexisting in one grain were imaged with high contrast. Bright field and centered dark field images revealed the pseudocubic (100) and (110) domain walls had developed in some regions of the same grain with normal ferroelectric macro‐domain features, and bend contours and distorted domain walls were seen. Defects with the features of low angle grain boundaries, dislocations, and phase boundaries were also observed. Uneven distribution of internal stress and coexistence of multiphases and multidomains in individual grains were considered to be responsible for the frequency relaxor behavior observed in these materials. A model of the evolution of the microstructures with the decrease of temperature is presented.
Influence of Synthesis Temperature on the Defect Structure of Boron Carbide: Experimental and Modeling Studies
Authors: Anselmi‐Tamburini Umberto , Munir Zuhair A. , Kodera Yasuhiro , Imai Takahito , Ohyanagi Manshi
Published: May 2005

Boron carbide (B4C) was synthesized from the elements at temperatures ranging from 1300° to 2100°C using the spark plasma synthesis method. Significant densification commenced at about 1500°C and was accompanied by a corresponding decrease in the defect structure of this carbide. Changes in the X‐ray diffraction patterns were in agreement with predictions of simulation studies based on the presence of twins. Transmission electron microscopy observations were consistent with the experimental observations and the modeling predictions.
Criteria for Flame‐Spray Synthesis of Hollow, Shell‐Like, or Inhomogeneous Oxides
Authors: Jossen R. , Pratsinis S. E. , Stark W. J. , Mädler L.
Published: May 2005

The influence of metal precursor and solvent composition on the morphology of SiO2, Bi2O3, and other oxide particles made by flame spray pyrolysis (FSP) was investigated. Silica precursors with boiling points Tbp=299–548 K dissolved in xylene were used as well as different solvents (Tbp=308–557 K) with tetraethyl‐orthosilicate (TEOS) as the silica precursor. For Bi2O3, nonvolatile bismuth nitrate pentahydrate was dissolved in solvents with Tbp=338–468 K. Product powders were characterized by nitrogen adsorption, X‐ray diffraction, and scanning and transmission electron microscopy. From these data as well as from the literature of FSP synthesis of Bi2O3, CeO2, MgO, ZnO, Fe2O3, Y2O3, Al2O3, and Mg–Al spinel, it is inferred that hollow/inhomogeneous particles are formed at low combustion enthalpy densities and when the solvent boiling point is comparable or smaller than the precursor melting or decomposition point.
Fabrication of an Anode‐Supported Gadolinium‐Doped Ceria Solid Oxide Fuel Cell and Its Operation at 550°C
Authors: Oishi N. , Atkinson A. , Brandon N. P. , Kilner J. A. , Steele B. C. H.
Published: May 2005

Ce0.9Gd0.1O2−x (CGO) layers were deposited onto nonconductive porous NiO–CGO supports by electrophoretic infiltration, and then compacted by isostatic pressing to achieve a high packing density of the deposited layer. The bilayers were sintered to give dense CGO layers at 1290°C in air. A fuel cell comprising an La0.6Sr0.4Co0.2Fe0.8O3−x cathode, a 10‐μm CGO electrolyte, and a Ni–CGO anode was tested at 550°C with humidified 10% H2 and air. The cell showed an open circuit voltage of 0.86 V and delivered a steady current of about 470 mA/cm2 at a terminal voltage of 0.24 V.
Multilayer Actuator Composed of PZN–PZT and PZN–PZT/Ag Fabricated by Co‐Extrusion Process
Authors: Yoon Chang‐Bun , Koh Young‐Hag , Park Gun‐Tae , Kim Hyoun‐Ee
Published: May 2005

A multilayer ceramic actuator composed of piezoelectrically active Pb(Zn1/3Nb2/3)0.2–Pb(Zr0.5Ti0.5)O0.8 (PZN–PZT) layers and electrically conducting PZN–PZT/Ag layers was fabricated by the co‐extrusion process. For the piezoelectric layers, PZN–PZT, which is sinterable at a low temperature (900°C), was used. For the conducting layers, a PZN–PZT/Ag composite, made by mixing silver particles with the PZN–PZT matrix, was employed. For the co‐extrusion process, piezoelectric and conducting feedrods were made by mixing the PZN–PZT and PZN–PZT/Ag, respectively, with a thermoplastic polymer. The initial feedrods, which were composed of five 3 mm‐thick PZN–PZT layers, two 1.5 mm‐thick PZN–PZT layers, and six 1 mm‐thick PZN–PZT/Ag layers, were co‐extruded through a 24 mm × 2 mm reduction die at 105°C to produce continuous multilayered green sheets. The sheets were stacked, warm pressed, and sintered at 900°C for 4 h after binder burnout. The sintered multilayer actuator showed distinct layers without any reaction products or cracks at the interface. The thicknesses of the piezoelectric and conducting layers were about 200 and 70 μm, respectively. The displacement of the multilayer actuator, composed of 40 piezoelectric layers (with a total height of 10.8 mm), was about 10 μm at an applied voltage of 500 V.
A Novel Sodium Silicate Fluoride Solution and a H2 Gas Formed by a Reaction Between Si and an Aqueous Solution of NaOH and NaF
Authors: Tsuyumoto Isao
Published: May 2005

Oxidation of Si in an alkali solution has attracted much attention to produce hydrogen gas from Si wastes. It was found that hydrogen gas was generated from Si in NaOH and NaF solution with more than 10 times reaction rate than in the NaOH solution. The reaction by‐product was a sodium silicate fluoride, Nax+zSiyO2y+x/2Fz solution, and it proved to transform to a glass foam by boiling. The Raman spectrum suggested that the silicon and oxygen atoms in the silicate anions were arranged in a sheet‐like structure. This may affect the behavior to form the glass foam.
Bonding of Cement Clinker onto Doloma‐Based Refractories
Authors: Guo Zongqi , Palco Stefan , Rigaud Michel
Published: May 2005

Adherence ability of cement clinker on doloma refractories was investigated using a specially designed sandwich test conducted at 1550°C for 30 min, under a load of 5.3 kPa. Fractional factorial experiments determined that silica ratio, particle size, and alumina ratio of raw meal had significant effects on the reactions between the clinker and the refractory. Silica ratio was found to be the most prominent factor influencing the adherence strength of the clinker on the surface of doloma bricks. Doloma refractory, having an excess of free lime, reacts with clinker to form additional C3S at the interface, which is greatly beneficial to adherence strength. The interface of doloma/clinker with low silica ratio is covered with a continuous MgO‐enriched layer, which is formed from the CaO reacting with the raw meal in presence of a large amount of liquid phase generated in the clinker. This layer reduced the adherence strength of clinker on doloma. With high silica‐ratio raw meal, clinker and doloma form a C3S‐rich layer at the interface, improving strongly the adherence strength of clinker on the brick.
Effect of External Lubricant on Mechanical Properties of Dry‐Pressed Green Bodies
Authors: Uppalapati Maruti , Green David J.
Published: May 2005

Tensile strength and fracture toughness of uniaxially compacted spray‐dried ferrite powders, with and without external lubricant were measured. The addition of external lubricant significantly increased the fracture strength and decreased the strength variability. The external lubricant also led to an increase in fracture toughness and a decrease in the critical flaw size. Scanning electron microscopy examination of fracture surfaces showed an increase in the amount of transgranular fracture for the pellets compacted from the externally lubricated powder. It was concluded that the external lubricant strengthened the bonds between the spray‐dried granules, thereby increasing the fracture toughness and reducing the critical flaw size. X‐ray tomography of pellets showed that there was no appreciable difference in density gradients between the samples.
Photoluminescence Properties of Nanocrystalline ZnO Ceramics Prepared by Pressureless Sintering and Spark Plasma Sintering
Authors: Wang Jinmin , Gao Lian
Published: May 2005

Nanocrystalline ZnO ceramics with grain sizes of ∼100 nm were prepared by pressureless sintering at 800°C for 2 h and spark plasma sintering (SPS) at 550°C for 2 min, respectively. Excellent green emission properties were obtained in the ZnO ceramic prepared by the SPS process and in the pressureless‐sintered ZnO ceramic prepared at 1000°C for 2 h, which are attributed to the vacuum ambience of the SPS process and the sublimeness of the interstitial Zn at >900°C in air, respectively.
Decrystallizing Solid Crystalline Titania, Without Melting, Using Microwave Magnetic Fields
Authors: Roy Rustum , Fang Yi , Cheng Jiping , Agrawal Dinesh K.
Published: May 2005

TiO2—a prototype ceramic—was decrystallized in a 2.45 GHz AC magnetic field in a single mode TE103 applicator. The titania powders were synthesized by a sol–gel process and pressed into circular pellets. The pellets were very slightly reduced at 1273 K in a reducing atmosphere. The reduced pellets were introduced into the single mode microwave cavity and placed at the magnetic field maximum node and exposed for 10–30 s in a forming gas atmosphere. The reacted samples were then characterized by XRD, SEM, Raman, and TEM. The data presented in this note demonstrate that a very short treatment in the AC magnetic field at 2.45 GHz can transform rutile structure oxides to a noncrystalline state.
Composition of Periclase and Calcium‐Silicate Phases in Magnesia Refractories Derived from Natural Microcrystalline Magnesite
Authors: Lampropoulou Paraskevi G. , Katagas Christos G. , Papamantellos Dimitrios C.
Published: May 2005

Mineralogical and microstructural properties of sintered and fused magnesia grains and refractory bricks derived from natural magnesite were examined. Although their CaO/SiO2 ratios can be used to approximate their mineralogical compositions, detailed X‐ray diffraction (XRD) and scanning electron microscopy (SEM) studies revealed significant deviations from the expected phase assemblages. Their microstructures vary widely in terms of proportions of direct periclase bonding, amounts and phase constitution of the siliceous bonding, and the size and composition of the periclase crystals. An exceptionally high solid solubility of CaO in periclase crystals was detected. Most of the phases of the siliceous bond exhibit nearly stoichiometric compositions and show intriguing substitutions.
Preparation and Photoluminescence of Partially Filled ZnO Microtubes Using Block Copolymers
Authors: Huang Qing , Gao Lian
Published: May 2005

Partially filled ZnO microtubes were synthesized in large scale using block copolymers. The growth mechanism of this unique construction is proposed on the basis of adsorption of block copolymers on {0002} plane of wurtzite ZnO. The photoluminescence property of these unique ZnO microtubes is also studied using a Xe lamp as the excitation source at room temperature. Blue emission band at 425 nm is a much stronger ultraviolet emission band, which is due to laminar structure of ZnO microtubes.
Damage‐Free and Short Annealing of Pb(Zr,Ti)O3 Thick Films Directly Deposited on Stainless Steel Sheet by Aerosol Deposition with CO2 Laser Radiation
Authors: Baba So , Akedo Jun
Published: May 2005

Pb(Zr,Ti)O3 (PZT) thick films directly deposited onto stainless steel (SS) sheets by the aerosol deposition method were annealed by CO2 laser (CL) radiation. The surface brilliance of the SS sheets was not influenced by thermal heating and the temperature of the reverse side of the film (i.e., the SS sheet) was measured at 150°C or less. The remanent polarization, coercive field values, and the dielectric constant are 27.8 μC/cm2, 31.6 kV/cm, and 1366, respectively. The diffusion layer between the PZT and the SS sheet was minimized by the use of CL radiation compared with using an electric furnace.
Preparation of Zirconia Base Solid Solution Nanopowder by Exothermal Solid‐State Synthesis
Authors: Huang Chuanyong , Guo Ruyan , Tang Zilong , Zhang Zhongtai
Published: May 2005

A new method is put forward to prepare nanometer zirconia base solid solution by exothermal solid‐state synthesis. This method is realized by agitating solid mixture of sodium hydroxide, zirconium oxychloride, and yttrium/calcium nitride. Fresh and final powders are studied by X‐ray fluorescence, X‐ray photoemission spectroscopy, X‐ray diffraction, and transmission electron microscopy. The results show the obtained tetragonal/cubic zirconia solid solution nanopowders are highly pure and distribute around 5 nm. It is suggested that the coordinated water of zirconium oxychloride acts as micro medium and the nuclei of solid solution are formed under the superalkaline environment and grow during heat treatment. This method may be useful to prepare other metal oxide nanopowders.
Fabrication of TiO2–SiO2 Photonic Crystals with Diamond Structure
Authors: Kanehira Shingo , Kirihara Soshu , Miyamoto Yoshinari
Published: May 2005

Ceramic photonic crystals with diamond structure were fabricated using stereolithography and successive sintering. The green body of an epoxy resin incorporating 10 vol% TiO2–SiO2 was formed by stereolithography and then heated in air at 1100°–1400°C for 2 h. The sintered products maintained the diamond structure with a linear shrinkage ratio of about 57% and a porosity of 38%. The ceramic photonic crystal with eight unit cells showed a photonic band gap at the center frequency of 23.5 GHz. This fabrication method of three‐dimensional (3D) ceramic photonic crystals is applicable to other 3D structural ceramics and does not require any molding techniques.
Microstructure and Mechanical Properties of In Situ Produced TiC/TiB2/MoSi2 Composites
Authors: Li Jianlin , Bai Guangzhao , Jiang Dongliang , Tan Shouhong
Published: May 2005

A novel microstructure of in situ produced TiC/TiB2/MoSi2 composite and its mechanical properties were investigated. The results indicate that TiC/TiB2/MoSi2 composites can be fabricated by reactive hot pressing the mixed powders of MoSi2, B4C, and Ti. A novel microstructure consisting of hollow particles of TiC and TiB2 grains in an MoSi2 matrix was obtained. Grains of in situ produced TiC and TiB2 were much finer, from 100 to 400 nm. During the fracture process, hollow particles relieved crack tip stress, encouraging crack branching and changing the original direction of the main crack. The highest bending strength of this composite achieved was 480 MPa, twice that of monolithic MoSi2, and the greatest fracture toughness of the composite reached 5.2 MPa·m1/2.
Disorder and Dynamics in Pollucite from 133Cs and 27Al NMR
Authors: Ashbrook Sharon E. , Whittle Karl R. , Le Pollès Laurent , Farnan Ian
Published: May 2005

Pollucite, CsAlSi2O6, a Cs polymorph of leucite (KAlSi2O6), has been proposed for ceramic immobilization of 135Cs and 137Cs fission products. 133Cs NMR of both low‐ (tetragonal) and high‐temperature (cubic) forms of pollucite exhibit a considerable distribution of local Cs environments. 29Si and 27Al NMR data from directly prepared pollucite show greater Al/Si disorder than either leucite, or pollucite produced by ion exchange. Little evidence for Cs motion is observed in tetragonal or cubic pollucite, and only at high temperatures (∼850°C) is any substantial dynamic behavior detected. Dynamic NMR lineshape calculations allow a determination of the frequency of Cs motion and diffusivity.