bluuebunny/crossref_metadata_2025 huggingface dataset:
Early childhood malnutrition predicts depressive symptoms at ages 11–17
Authors: Galler J.R. , Bryce C.P. , Waber D. , Hock R.S. , Exner N. , Eaglesfield D. , Fitzmaurice G. , Harrison R.
Published: March 2010

Background:  We examined the prevalence of depressive symptoms in Barbadian youth with histories of infantile malnutrition and in a healthy comparison group and the extent to which the effect of malnutrition was mediated/moderated by maternal depression.

Methods:  Depressive symptoms were assessed using a 20‐item scale administered to youths (11–17 years of age) who had experienced an episode of protein‐energy malnutrition (marasmus or kwashiorkor) during the first year of life and in a comparison group of healthy youths without a history of malnutrition. Their mothers completed the same questionnaire on the same test on three occasions when their children were 5–17 years of age at 2–5‐year intervals.

Results:  The prevalence of depressive symptoms was elevated among previously malnourished youth relative to healthy comparison children (p  <  .001). When youth depression scores were subjected to a longitudinal multiple regression analysis, adjusting for the effect of maternal depressive symptoms, significant effects due to the history of early childhood malnutrition remained and were not discernibly attenuated from an unadjusted analysis. We also found significant independent effects of maternal depressive symptoms on youth depressive symptoms.

Conclusion:  Early childhood malnutrition contributed independently to depressive symptoms in youths who experienced a significant episode of malnutrition in the first year of life. This relationship was not mediated or moderated by the effects of maternal depression. Whether the later vulnerability to depression is a direct effect of the episode of malnutrition and related conditions early in life or whether it is mediated by the more proximal neurobehavioral effects of the malnutrition remains to be determined.
Biological stoichiometry of plant production: metabolism, scaling and ecological response to global change
Authors: Elser J. J. , Fagan W. F. , Kerkhoff A. J. , Swenson N. G. , Enquist B. J.
Published: March 2010

Biological stoichiometry theory considers the balance of multiple chemical elements in living systems, whereas metabolic scaling theory considers how size affects metabolic properties from cells to ecosystems. We review recent developments integrating biological stoichiometry and metabolic scaling theories in the context of plant ecology and global change. Although vascular plants exhibit wide variation in foliar carbon : nitrogen : phosphorus ratios, they exhibit a higher degree of ‘stoichiometric homeostasis’ than previously appreciated. Thus, terrestrial carbon : nitrogen : phosphorus stoichiometry will reflect the effects of adjustment to local growth conditions as well as species’ replacements. Plant stoichiometry exhibits size scaling, as foliar nutrient concentration decreases with increasing plant size, especially for phosphorus. Thus, small plants have lower nitrogen : phosphorus ratios. Furthermore, foliar nutrient concentration is reflected in other tissues (root, reproductive, support), permitting the development of empirical models of production that scale from tissue to whole‐plant levels. Plant stoichiometry exhibits large‐scale macroecological patterns, including stronger latitudinal trends and environmental correlations for phosphorus concentration (relative to nitrogen) and a positive correlation between nutrient concentrations and geographic range size. Given this emerging knowledge of how plant nutrients respond to environmental variables and are connected to size, the effects of global change factors (such as carbon dioxide, temperature, nitrogen deposition) can be better understood.

Contents

Summary
593

I.
Introduction
594

II.
Variation in plant C : N : ratios: how much and what are the sources?
595

III.
The growth rate hypothesis in terrestrial plants and the scaling of whole‐plant N : P stoichiometry and production
597

IV.
Scaling from tissues to whole plants
599

V.
Applications: large‐scale patterns and processes associated with plant stoichiometry
601

VI.
Global change and plants: a stoichiometric scaling perspective
603

VII.
Synthesis and summary
604

Acknowledgements
605

References
605
Sonic Hedgehog signaling in the mammalian brain
Authors: Traiffort Elisabeth , Angot Elodie , Ruat Martial
Published: March 2010

J. Neurochem. (2010) 113, 576–590.

The discovery of a Sonic Hedgehog (Shh) signaling pathway in the mature vertebrate CNS has paved the way to the characterization of the functional roles of Shh signals in normal and diseased brain. Shh is proposed to participate in the establishment and maintenance of adult neurogenic niches and to regulate the proliferation of neuronal or glial precursors in several brain areas. Consistent with its role during brain development, misregulation of Shh signaling is associated with tumorigenesis while its recruitement in damaged neural tissue might be part of the regenerating process. This review focuses on the most recent data of the Hedgehog pathway in the adult brain and its relevance as a novel therapeutic approach for brain diseases including brain tumors.
Stroke patients’ delay of emergency treatment
Authors: Hjelmblink Finn , Holmström Inger , Kjeldmand Dorte
Published: March 2010

Scand J Caring Sci; 2010; 24; 307–311
 
Stroke patients’ delay of emergency treatment

Treatment of stroke victims with fibrinolysis should take place within a time limit of 3 hours. In spite of comprehensive endeavours to reduce hospital arrival time, too many patients still delay arrival beyond this time limit. This qualitative case study explored the meaning of acute stroke and treatment to four patients with more than 24‐hour delayed arrival. The setting of the study was the catchment area of a university hospital. Semi‐structured interviews were analysed through the empirical psychological, phenomenological method. An essence was found which was constituted by four themes. The essence of stroke symptoms and treatment was: ‘Threatened control of bodily function, autonomy and integrity’. When the patients fell ill they acted as if nothing had happened. They treated their body like a defective device. In encounters with physicians they demanded to be met as a person by a person; otherwise they rejected both the physician and her or his prescriptions. They did not involve their near ones in decision‐making. The conclusions were the following: Health care information about how to act in cases of early stroke symptoms may need to imbue people with an understanding of how early treatment of neurological symptoms and preserved control of life are intimately connected. Furthermore emergency care of acute stroke patients might need to take place in an organisation where patients are sure to be met by physicians as a person by a person.
Dependency in autonomous caring – night nurses’ working conditions for caring in nursing
Authors: Gustafsson Christine , Fagerberg Ingegerd , Asp Margareta
Published: March 2010

Scand J Caring Sci; 2010; 24; 312–320
 
Dependency in autonomous caring – night nurses’ working conditions for caring in nursing

Few research studies have focused on nurses’ working conditions for caring provided at night, and these studies have mainly described nurses’ work in hospital settings, not in a municipal, social‐care context. In Swedish municipal care, nurses have responsibility for hundreds of older people in need of care. This working condition compromises caring encounters; instead the nurses’ caring is mainly mediated through care staff (or relatives). In considering that caring based on caring encounters is fundamental to ethical nursing practice questions leads to the aim: to explore Swedish municipal night nurses’ experiences of their working conditions for caring in nursing. All municipal night‐duty nurses (n = 7) in a medium‐sized community in Sweden participated in interviews, while six of them also wrote diaries. Thematic content analysis has been used in analysing the data. The findings revealed that the nurses experienced their working conditions for caring in nursing in the themes of Dependency in the Organisation and Other Staff, Vocational Responsibility, Deficiency in Conditions for Caring and Autonomous Caring. The findings illustrate privileged, as well as, poor working conditions for caring in nursing. The nurses’ role as consultants emerge as their main function. The consultant function implies that nurses do not participate in ordinary bed‐side caring, which makes it easier for them to find time for caring in situations that arise when nurses’ skills, expertise and authority are called upon. Conversely the consultancy function entails short‐term solution of complex caring problems, which can signify deficient caring due to prevailing working conditions. The findings also point to nurses’ possible problems in fulfilling their own and vocational demands for ethics in the practice of caring in nursing related to existing working conditions.
Positive life orientation–an inner health resource among older people
Authors: Fagerström Lisbeth
Published: March 2010

Scand J Caring Sci; 2010; 24; 349–356
 
Positive life orientation–an inner health resource among older people

As pertains to life orientation, the study's conceptual framework demonstrates the importance of close relationships, meaning in life, and the strength of individuals to look forward and make plans for future. The aim of this study is to discover, in relation to background factors such as language, living situation, and culture, how people aged 65 and 75 experience life orientation. The study is a population‐based cross‐sectional survey with its material taken from 3,370 questionnaires which included the six‐question Life Orientation scale. The SPSS static program, version 14.0, was used for all calcuations and the Chi‐squared test was applied to determine if any significant differences between the groups existed. As seen in this study, most respondents aged 65 (85%) and 75 (73.2%) experienced a high degree of positive life orientation, clearly expressing a zest for life (93.5%), overall satisfaction with their lives (88.4%), and feelings of being needed (83.7%). Lower scores were given for never/seldom being depressed/sad (55.3%) and never/seldom feeling lonely (71.8%). Approximately every second respondent (51.9%) had plans for the future. A clear decreasing trend was seen in all questions for respondents aged 75 in comparison to those aged 65: only ``are you satisfied with life?'' showed no significant differences. Language/culture seems to clearly affect experiences of life orientation and well‐being. Additionally, older people living alone reported significantly more negative response to all dimensions of life orientation. Positive life orientation is an important inner health resource for older. Accordingly, health promotion for older people should focus on facilitating the maintenance of important and close relationships and should include supporting older people's need to be needed.
A NEW METHOD FOR EXTRACTION, ISOLATION AND TRANSESTERIFICATION OF FREE FATTY ACIDS FROM ARCHAEOLOGICAL POTTERY
Authors: GREGG M. W. , SLATER G. F.
Published: March 2010

This paper presents evidence for increased recovery of organic residues from archaeological pottery through use of a microwave‐assisted liquid chromatography protocol. C16:0 and C18:0 saturated fatty acids were obtained from archaeological potsherds recovered from nine Neolithic settlements in the Middle East dating between 4700 and 7300 cal bc, including materials that had not produced evidence for the survival of any lipid species through use of ‘conventional’ solvent extraction techniques. Compound‐specific isotopic analyses of C16:0 and C18:0 fatty acids in potsherd extracts subsequently revealed δ13C/δ12C compositions consistent with modern subcutaneous fats of wild boar and goats pastured on lands adjacent to the Jordan Valley, and residues from a modern pottery vessel used in the manufacturing of butter, cheese and yogurt in central Turkey. These results are presented as an illustration of capabilities of the microwave‐assisted recovery protocol. The reclamation of saturated and unsaturated fatty acids from archaeological pottery fragments recovered from a number of the earliest ceramic horizons in the Middle East is herewith reported, and the extraction methods and instrumental analytical techniques are described.
Moral Hazard Matters: Measuring Relative Rates of Underinsurance Using Threshold Measures
Authors: Abraham Jean Marie , DeLeire Thomas , Royalty Anne Beeson
Published: March 2010

Objective. To illustrate the impact of moral hazard for estimating relative rates of underinsurance and to present an adjustment method to correct for this source of bias.

Data Sources/Study Setting. Secondary data from the 2005 Medical Expenditure Panel Survey (MEPS) are used in this study. We restrict attention to households that report having employer‐sponsored insurance (ESI) for all members during the entire 2005 calendar year.

Study Design. Individuals or households are often classified as underinsured if out‐of‐pocket spending on medical care relative to income exceeds some threshold. In this paper, we show that, without adjustment, this common threshold measure of underinsurance will underestimate the number with low levels of insurance coverage due to moral hazard. We propose an adjustment method and apply it to the specific case of estimating the difference in rates of underinsurance among small‐ versus large‐firm workers with full‐year ESI.

Data Collection/Extraction. Data were abstracted from the MEPS website. All analyses were performed in Stata 9.2.

Principal Findings. Applying the adjustment, we find that the underinsurance rate of small‐firm households increases by approximately 20 percent with the adjustment for moral hazard and the difference in underinsurance rates between large‐firm and small‐firm households widens substantially.

Conclusions. Adjusting for moral hazard makes a sizeable difference in the estimated prevalence of underinsurance using a threshold measure.
The EU and the Welfare State are Compatible: Finnish Social Democrats and European Integration
Authors: Raunio Tapio
Published: March 2010

This article examines how the Finnish Social Democratic Party has adapted to European integration. The analysis illustrates that the Social Democrats have successfully argued to their electorate that the objectives of integration are compatible with core social democratic values. Considering that Finland was hit by a severe recession in the early 1990s, discourse about economic integration and monetary stability facilitating the economic growth that is essential for job creation and the survival of domestic welfare state policies sounded appealing to SDP voters. Determined party leadership, support from trade unions and the lack of a credible threat from the other leftist parties have also contributed to the relatively smooth adaptation to Europe. However, recent internal debates about the direction of party ideology and poor electoral performances – notably in the European Parliament elections – indicate that not all sections within the party are in favour of the current ideological choices.
Ecological Trap for Desert Lizards Caused by Anthropogenic Changes in Habitat Structure that Favor Predator Activity
Authors: HAWLENA DROR , SALTZ DAVID , ABRAMSKY ZVIKA , BOUSKILA AMOS
Published: March 2010

Abstract: Anthropogenic habitat perturbation is a major cause of population decline. A standard practice managers use to protect populations is to leave portions of natural habitat intact. We describe a case study in which, despite the use of this practice, the critically endangered lizardAcanthodactylus beershebensiswas locally extirpated from both manipulated and natural patches within a mosaic landscape of an afforestation project. We hypothesized that increased structural complexity in planted patches favors avian predator activity and makes these patches less suitable for lizards due to a heightened risk of predation. Spatial rarity of natural perches (e.g., trees) in arid scrublands may hinder the ability of desert lizards to associate perches with low‐quality habitat, turning planted patches into ecological traps for such species. We erected artificial trees in a structurally simple arid habitat (similar to the way trees were planted in the afforestation project) and compared lizard population dynamics in plots with these structures and without. Survival of lizards in the plots with artificial trees was lower than survival in plots without artificial trees. Hatchlings dispersed into plots with artificial trees in a manner that indicated they perceived the quality of these plots as similar to the surrounding, unmanipulated landscape. Our results showed that local anthropogenic changes in habitat structure that seem relatively harmless may have a considerable negative effect beyond the immediate area of the perturbation because the disturbed habitat may become an ecological trap.
Wood‐Derived Porous SiC Ceramics by Sol Infiltration and Carbothermal Reduction
Authors: Herzog Andreas , Klingner Raoul , Vogt Ulrich , Graule Thomas
Published: March 2010

A new method for transforming wood structures into ceramic by carbothermal reduction of silica and carbonized wood has been developed. Application of this technique allows the preservation of wood microstructures in the ceramic state and the conversion of wood components without constraints in component size. The chosen infiltration technique of silica sol incorporation into carbonized wood structures is examined in terms of sol and wood type, carbonization conditions of the wood, and thickness of the infiltrated carbon body. Ceramization conditions were optimized, and the reaction mechanism is discussed.
Growth Mechanism of Nanometer‐Sized SiC and Oxidation Resistance of SiC‐Coated Diamond Particles
Authors: Morisada Yoshiaki , Miyamoto Yoshinari , Moriguchi Hideki , Tsuduki Katsunori , Ikegaya Akihiko
Published: March 2010

Diamond particles were coated with a thin SiC layer by the reaction of SiO vapor with diamond, and the growth mechanism of SiC as well as the oxidation resistance of the SiC‐coated diamond were studied. The growth process of the SiC layer can be separated into two steps. In the first step, a thin layer of SiC with a thickness of about 15 nm is formed due to the reaction between SiO vapor and diamond. In the second step, nanometer‐sized SiC granules are deposited on the SiC layer by the reaction between SiO vapor and CO. The apparent activation energy for the formation of SiC layer on diamond was found to be 100 kJ/mol. This value suggests that the SiC coating process occurred mainly by vapor‐phase reaction. The oxidation resistance of the SiC‐coated diamond was improved depending on the thickness of the SiC layer. Oxidation of the SiC‐coated diamond particles began at 950°C, which was 400°C higher than that of uncoated diamond.
Encapsulation of Hydroxyapatite Microspheres with Fluorapatite Using a Diffusion Process
Authors: Rodríguez‐Lorenzo Luis M. , Gross Kārlis A.
Published: March 2010

Modification of hydroxyapatite surfaces can improve the properties of biomedical devices. The objective of this work was to encapsulate hydroxyapatite particles with a fluorapatite layer. A suspension of hydroxyapatite microspheres was prepared in a solution at different pH and treated with ammonium fluoride. pH, calcium, and fluoride were monitored in real time and particles subjected to fluoride analysis. After addition of fluoride, it was found that more material is released from the particle surface at low pH conditions, but leads to a high fluoride uptake from solution. Low solution fluoride levels produce a fluorapatite layer, but higher fluoride levels produce calcium fluoride.
Development of Mica Glass‐Ceramic Glazes
Authors: Romero Maximina , Rincón Jesús Ma. , Acosta Anselmo
Published: March 2010

The effect of iron content on crystallization of a mica glaze as coating for fast firing stoneware substrates has been investigated. Measurements by differential thermal analysis (DTA) combined with X‐ray diffraction (XRD) and scanning electron microscopy (SEM) have shown the development of preferential crystal orientation in the mica glass‐ceramic glaze. By comparison with amorphous and partly crystalline glazes, an enhancement of the mechanical properties of coatings with aligned and interlocked crystals of mica has been observed.
Influence of Compaction and Granulation Processes on the Properties of Soft Magnetic Ceramics
Authors: Zaspalis Vassilios , Tsakaloudi Vassiliki
Published: March 2010

The granulation and compaction processes are investigated in relation to the influence they have on the magnetic permeability and electromagnetic power losses of conventionally prepared polycrystalline manganese‐zinc ferrites. It appears that, during granulation by spray‐drying, rapid evaporation conditions may be reached at the internal of the under drying droplets, giving rise to the formation of large void defects in the interior of the granulate. Those defects may resist compaction and also be present in the compacted specimens, eventually leading to large intragranular isolated pores and lower densities at the sintered material; the magnetic properties of the material are therefore negatively influenced. Compaction at high pressures (e.g., >500 kg cm−2) may compensate for the existence of inflation defects by causing their removal on compaction. The previous phenomenon is absent in granulates made by the roll granulation process that exhibit, in general, a better compaction, sintering, and magnetic behavior when compared to spray‐drying granulates at conditions where void formation takes place.
Preparation of Spherical, Solid Barium Titanate Particles with Uniform Composition at High Precursor Concentration by Spray Pyrolysis
Authors: Gao Lian , Xu Huarui
Published: March 2010

Hydrolysis‐assisted spray pyrolysis (HASP) using dimethyl oxalate as hydrolyte was found to be applicable to precipitation of solid, spherical BaTiO3 powder with uniform composition when the stock solution concentration was high (>1.0M). Solid, dense powder with uniform composition was successfully obtained because barium titanium oxalate was prepared from partial hydrolysis of dimethyl oxalate and coprecipitation of oxalate with barium and titanium during the hydrolysis–precipitation process, and then the oxalate particles became seeds in the following process. The sintered sample from the as‐prepared BaTiO3 powder led to a higher dielectric constant and lower loss.
Effect of MnO2 Addition on the Structure and Electrical Properties of Pb(Zn1/3Nb2/3)0.20(Zr0.50Ti0.50)0.80O3 Ceramics
Authors: Hou Yudong , Zhu Mankang , Gao Feng , Wang Hao , Wang Bo , Yan Hui , Tian Changsheng
Published: March 2010

Pb(Zn1/3Nb2/3)0.20(Zr0.50Ti0.50)0.80O3 ceramics of pure perovskite structure were prepared by the two‐stage method with the addition of 0–3.0 wt% MnO2 and their piezoelectric properties were investigated systematically. The MnO2 addition influences in a pronounced way both the crystal structure and the microstructure of the materials. The materials are transformed from the tetragonal to the rhombohedral structure, and the grain size is enhanced when manganese cations are added. The distortion of crystal structure for samples with MnO2 addition can be explained by the Jahn–Teller effect. The values of electromechanical coupling factor (kp) and dielectric loss (tan δ) are optimized for 0.5‐wt%‐MnO2‐doped samples (kp= 0.60, tan δ= 0.2%) and the mechanical quality factor (Qm) is maximized for 1.0‐wt%‐MnO2‐doped samples (Qm= 1041), which suggests that oxygen vacancies formed by substituting Mn3+ and Mn2+ ions for B‐site ions (e.g., Ti4+ and Zr4+ ions) in the perovskite structure partially inhibited polarization reversal in the ferroelectrics. The ceramics with 0.50–1.0 wt% MnO2 addition show great promise as practical materials for piezoelectric applications.
Base‐Metal‐Electroded BaTiO3 Capacitor Materials with Duplex Microstructures
Authors: Lin I‐Nan , Yang Wei‐Chun , Hu Chen‐Ti
Published: March 2010

The effect of dopants and processing conditions on the dielectric properties of base‐metal‐electroded materials was investigated. BaTiO3 materials simultaneously doped with MgO and Y2O3 additives can achieve small capacitance variation (ΔC/C), which meets the X7R specification, when the proportion of additives is abundant enough and the materials are not over‐fired. Presumably, small ΔC/C values of thus obtained materials are the result of the formation of core–shell structure, which requires stringent control of material processing conditions. In contrast, X7R‐type materials can be obtained in a much wider processing window, when prepared by mixing two BaTiO3 materials of suitable dielectric constant–temperature (K–T) characteristics. Duplexed materials prepared from these two end‐point BaTiO3 materials with ratios ranging from 3:1 to 1:2 exhibit K–T behavior within the X7R specification, provided that one of the components possesses flat K–T behavior. Moreover, the dielectric properties of these materials were simulated using a simplified microstructural model. Simulation results indicate that the effective dielectric constant of core–shell materials, (Ke)CS, varies significantly not only with the dielectric properties of cores and shells, but also with the shell‐to‐core thickness ratio, whereas the effective dielectric constant of duplexed materials, (Ke)D, can be maintained at a very small ΔC/C value for a wide range of end‐point constituent ratios, which agrees very well with the measured K–T properties for the materials.
Effects of Silver on Barium Titanate as a Function of Stoichiometry
Authors: Byrne Tiffany A. , Cann David P.
Published: March 2010

This work examines the effects of Ag on stoichiometric and nonstoichiometric BaTiO3 in terms of the unit cell dimensions, the polycrystalline microstructure, and the dielectric properties. Stoichiometric BaTiO3 and compositions with 0.5 mol% TiO2 excess and 0.5 mol% BaO excess were prepared via solid‐state synthesis with varying amounts of Ag up to 0.3 mol%. Experimental results indicate that stoichiometry plays a significant role in the solubility of Ag and its effects on the physical properties. Overall, the solubility of Ag was negligible in stoichiometric BaTiO3. However, compositions with excess TiO2 stabilized the solubility of Ag as evidenced from changes in the unit cell dimensions and dielectric properties. Based on these data, it is proposed that Ag occupies the A‐site in the perovskite structure with an upper limit of Ag solubility of 0.06 mol% Ag in BaTiO3 with 0.5 mol% excess TiO2. Dielectric measurements showed that Ag concentrations approaching 0.3 mol% gave rise to an increase in the space charge effect, especially at temperatures above TC. In both nonstoichiometric compositions, the presence of a liquid Ag phase during thermal processing was found to affect microstructural development and sintering.
Effect of Yttrium Aluminum Garnet Additions on Alumina‐Fiber‐Reinforced Porous‐Alumina‐Matrix Composites
Authors: Cinibulk Michael K. , Keller Kristin A. , Mah Tai‐Il
Published: March 2010

The effects of incorporating yttrium aluminum garnet (YAG) into a porous alumina matrix reinforced with Nextel 610 alumina fibers were investigated. Composites with various amounts of YAG added to the matrix were prepared to determine its effect on retained tensile strengths after heating to 1100° and 1200°C. Strengths of YAG‐containing composites were slightly lower than those of an all‐alumina‐matrix composite after heating for 5 h to 1100°C. However, after heating for 5 or 100 h at 1200°C, all the YAG‐containing composites displayed greater strengths and greater strains to failure than the all‐alumina composite. At the higher temperature, the presence of YAG is believed to inhibit the densification of the matrix, which helps to maintain higher levels of porosity and weaker interparticle bonding that allows for crack‐energy dissipation within the matrix. A reduction in grain growth of the fibers by the presence of segregated Y was also observed, which may also contribute to higher fiber strength, thereby increasing the retained strengths of the YAG‐containing composites.
Influence of Minor Ions on the Stability and Hydration Rates of β‐Dicalcium Silicate
Authors: Kim Young‐Min , Hong Seong‐Hyeon
Published: March 2010

The effects of Al3+, B3+, P5+, Fe3+, S6+, and K+ ions on the stability of the β‐phase and its hydration rate were studied in reactive dicalcium silicate (C2S, Ca2SiO4) synthesized using the Pechini process. In particular, the dependences of the phase stability and degree of hydration on the calcination temperature (i.e., particle size) and the concentration of the stabilizing ions were investigated. The phase evolution in doped C2S was determined using XRD, and the degree of hydration was estimated by the peak intensity ratio of the hydrates to the nonhydrates in 29Si MAS NMR spectra. The stabilizing ability of the ions varied significantly, and the B3+ ions were quite effective in stabilizing the β‐phase over a wide range of doping concentrations. The hydration results indicated that differently stabilized β‐C2S hydrated at different rates, and Al3+‐ and B3+‐doped C2S exhibited increased degree of hydration for all doping concentration ranges investigated. The effect of the doping concentration on degree of hydration was strongly dependent on the stabilizing ions.
Strength Evaluation of Piezoelectric Ceramics under Transient Thermal Environments
Authors: Wang Bao‐Lin , Mai Yiu‐Wing
Published: March 2010

The strength of piezoelectric ceramics is analyzed for a plate suddenly exposed to an environmental medium of different temperatures. The admissible temperature jump the material can sustain is studied using the stress‐ and fracture‐toughness‐based failure criteria. The critical parameters governing the level of the transient thermal stress in piezoelectric ceramics are identified. Solutions are obtained for the maximum thermal shock that the plate can sustain without failure, under the conditions that (i) maximum local tensile stress equals the tensile strength of the ceramic, and (ii) maximum stress intensity factor for representative pre‐existing cracks equals the fracture toughness of the ceramic.
Effect of Electrode Configuration on Phase Retardation of PLZT Films Grown on Glass Substrate
Authors: Choi Jong‐Jin , Kim Dal‐Young , Park Gun‐Tae , Kim Hyoun‐Ee
Published: March 2010

Lead lanthanum zirconate titanate (PLZT) thick films were deposited on a glass substrate using a methoxyethanol‐based sol–gel multicoating method. Two types of electrodes, a coplanar surface electrode and an embedded electrode, were deposited on the films to measure the phase retardation of the PLZT films by the Senarmont method. The quadratic electrooptic properties were measured as a function of the film thickness, for thicknesses ranging from 1 to 4 μm. The PLZT film with the embedded electrode structure showed a higher phase retardation value and enhanced electric breakdown resistance.
In Situ Formation of Metal Nanoparticles on Ceramic Surface
Authors: Suenaga Seiichi , Suetsuna Tomohiro , Harada Koichi , Fukasawa Takayuki
Published: March 2010

A new preparation method for nanocomposites is proposed in which nanometer‐scale nickel particles are precipitated homogeneously on the magnesia surface. Our approach is based on a conventional method that uses a reaction of difference in oxide stability in reductive atmosphere. We found that aluminum doping of the material precursor enabled preferential precipitation on the oxide substrate. We also have applied the preparation method for the nickel‐copper/magnesia system. An addition of copper was effective for reducing the particle diameter. We found that morphology created by the method could be controlled by varying precursor composition.
Dissolution and Separation of Ruthenium in Borosilicate Glass
Authors: Yamashita Masaru , Yamanaka Hiroshi , Sasage Ken‐ichi
Published: March 2010

The behavior of ruthenium oxide (RuO2) in aluminoborosilicate glass used for the stabilization of nuclear waste was investigated. It was found that 0.025 mass% RuO2 dissolved as Ru4+ in the glass at 1400°C, which caused the glass to turn yellow. When the RuO2 amount was 0.05 mass%, needle‐shaped crystals formed in the glass during slow cooling. If the added amount exceeded 0.1 mass% and the cooling rate was slow, it separated rapidly and the glass became pale after cooling. No dissolution of ruthenium was detectable after melting at 1200°C.
Increasing the Crystallinity of Hydroxyapatite Nanoparticles in Composites Containing Bioaffinitive Organic Polymers by Mechanical Stressing
Authors: Nemoto Rei , Wang Li , Aoshima Masahiro , Senna Mamoru , Ikoma Toshiyuki , Tanaka Junzo
Published: March 2010

Crystallinity of hydroxyapatite (HAp) in bioaffinitive disperse systems was increased by a wet mechanochemical treatment at room temperature. Silk fibroin (SF) and/or hyaluronic acid (HYA) were used as bioorganics. With the mechanochemical treatment, the crystallite size and the aspect ratio of HAp decreased and became closer to that of swine trabecular bone. Mechanochemical effects on the HAp nanocrystals were discussed in terms of coherent chemical interaction between HAp and bioorganics.
Synthesis of Nanocrystalline TiO2 Particles by Hydrolysis of Titanyl Organic Compounds at Low Temperature
Authors: Chen Xiaoquan , Gu Guobang , Liu Huanbin , Cao Zhennian
Published: March 2010

Fourier transform infrared analysis, nuclear magnetic resonance, and thermogravimetric analysis show that most of the solid product prepared from the reaction of Ti(OC4H9)4 and excess (CH3CO)2O is a mixture of titanyl organic compounds. Nanocrystalline TiO2 particles, which include anatase TiO2, rutile TiO2, and a mixture of anatase and rutile, can be obtained from hydrolysis of the titanyl organic compounds under normal pressure at 60°C. The particle size, shape, and formation process of the crystals have been studied using X‐ray diffraction and transmission electron microscopy. The specific‐surface‐area data for a rutile TiO2 sample and the powders obtained after calcination at different temperatures have been measured by the Brunauer–Emmett–Teller method.
Liquid‐Phase Growth of Small Crystals for Seeding α‐SiAlON Ceramics
Authors: Zenotchkine M. , Shuba R. , Chen I‐Wei
Published: March 2010

Single‐phase small crystals of Li‐, Mg‐, Ca‐, Y‐, Nd‐, and Yb‐α‐SiAlONs have been obtained by liquid‐phase sintering for various compositions and processing conditions. These crystals are suitable for seeding grain growth in α‐SiAlON ceramics. The influence of chemical and processing parameters (starting composition and powders, green density, liquid content, heating schedule, nitrogen pressure, and temperature) on the size and morphology of seed crystals has been investigated. The results are compared with those for β‐Si3N4 crystal formation, and the differences are discussed in terms of nucleation and growth kinetics during liquid‐phase sintering.
Selective Nucleation and Band‐Gap Widening of LiNbO3 Nanocrystals on an α‐Al2O3 Substrate
Authors: Lee Geun‐Hyoung
Published: March 2010

Selective nucleation of LiNbO3 nanocrystals on the steps was observed during the initial stage of LiNbO3 film growth in an α‐Al2O3 (0001) substrate with a multiatomic step structure. In addition, stress stored in the nanocrystals as a result of the different thermal expansion coefficients of the film and the substrate caused band‐gap widening. As the size of the nanocrystals decreased, the band gap shifted to a higher energy.
Dielectric Characteristics of Bismuth Oxide Solid Solutions with a Fluorite‐Like Crystal Structure
Authors: Valant Matjaz , Suvorov Danilo
Published: March 2010

A series of Bi2O3‐rich solid solutions with a fluorite‐like crystal structure have been synthesized and analyzed with respect to their dielectric properties as functions of temperature and frequency. The existence of several common dielectric characteristics indicates a strong influence of the fluorite prototype cell on the frequency and temperature dependence of the dielectric properties. These characteristics, common to Bi2O3 solid solutions with the face‐centered cubic δ structure, the tetragonal β structure, and the rhombohedral anti‐α‐AgI crystal structure, are (i) a frequency‐dispersive increase in permittivity and dielectric losses because of a space‐charge polarization, (ii) a frequency‐independent permittivity and a linear temperature dependence of permittivity with a positive trend in the low‐temperature range where the space‐charge polarization is insignificant, and (iii) two frequency‐dispersive relaxations above room temperature.
Laser‐Sintered Bismuth Germanate Ceramics as Scintillator Devices
Authors: Macedo Zélia Soares , Silva Ronaldo Santos , Valerio Mário Ernesto Giroldo , Martinez André Luiz , Hernandes Antonio Carlos
Published: March 2010

We have investigated the potential use of Bi4Ge3O12 (BGO) laser‐sintered ceramics in scintillator devices for radiation detection. Relevant results from the characterization made during the ceramic processing are presented, such as particle size analysis, X‐ray diffraction studies, and thermal analysis. Furthermore, we have compared the microstructure, relative density, thermoluminescent (TL) emission, and transparency degree of ceramic bodies sintered by CO2 laser heating with a reference set of ceramics sintered in an electrical furnace, and also with single crystals grown by the Czochralski technique. It was observed that the laser‐sintered BGO presented a relative density of 98% (±2%), better pore shrinkage, larger grains, and light transmission intensity 1.5 times higher than the BGO ceramics sintered in a furnace. The TL curves of all samples irradiated with UV and β−rays presented peaks at 75°, 102°, and 143°C, and provided strong indication that the intergrain defects have the same nature of the bulk defects and do not contribute with new traps in the temperature range studied. The relative areas of the total TL emission after β irradiation were 6,0:4,4:1 for the reference ceramic, laser sintered ceramic, and single crystal, respectively. For UV irradiated samples, this relation was 7,1:4,7:1. From these results, we have concluded that laser‐sintered ceramics have an amount of charge traps lower than the conventionally sintered BGO samples, thus having a higher radioluminescence yield.
Spectroscopic Nondestructive Evaluation of Environmental Barrier Coating Failure on Silicon‐Based Ceramics
Authors: Ramachandra Canumalla , Lee Kang N. , Tewari Surendra N. , DeGroot Wim A.
Published: March 2010

Environmental barrier coatings (EBCs) are external ceramic coatings on silicon‐based ceramic components to protect them from water vapor attack in combustion environments. A spectroscopic nondestructive technique to monitor the degradation of environmental barrier coatings was investigated. Lithium oxide was selected as a spectroscopic marker material after an extensive screening of various materials for their emissivity in simulated combustion environments. Spectral response of excited lithium atoms from mullite doped with 0.025–1 wt% lithium oxide was examined under an oxy‐acetylene flame. A three‐layer EBC (Si/Li2O‐doped mullite/BSAS) on a silicon carbide substrate, which had fine simulated cracks, showed significant lithium emission on exposure to the oxy‐acetylene flame, which demonstrated the potential of emission spectroscopy as a nondestructive evaluation tool to monitor EBC degradation.
Superplasticity‐like Deformation of Nanocrystalline Monoclinic Zirconia at Elevated Temperatures
Authors: Yoshida Michiyuki , Shinoda Yutaka , Akatsu Takashi , Wakai Fumihiro
Published: March 2010

The deformation behavior of nanocrystalline monoclinic ZrO2 polycrystals (nanocrystalline MZP) was studied at 1273–1373 K in compression tests. The deformation of nanocrystalline MZP was characterized by stress exponent (n= 2.5), grain‐size exponent (p= 2.5), and apparent activation energy (Q= 350 kJ/mol). The values of n and p were similar to the superplasticity of high‐purity Zn‐22% aluminum alloy. The strain rate of nanocrystalline MZP was faster than that of Y2O3‐stabilized tetragonal ZrO2 (Y‐TZP) at temperatures lower than the monoclinic‐tetragonal transition temperature. The strain rate of MZP gradually approached to that of Y‐TZP as the temperature increased to the transition temperature. The comparison of present data with published data suggested that trace amount of impurities affected the deformation behavior of MZP.
X‐ray Diffraction Methodology for the Microstructural Analysis of Nanocrystalline Powders: Application to Cerium Oxide
Authors: Leoni Matteo , Di Maggio Rosa , Polizzi Stefano , Scardi Paolo
Published: March 2010

The microstructural evolution of nanocrystalline ceria produced by sol–gel has been analyzed as a function of the calcination temperature employing a novel nondestructive method based on the modeling of the whole X‐ray diffraction pattern. The results have been thoroughly verified by transmission electron microscopy. A variation both in the average size and in the distribution of the crystalline domains is evidenced. In addition, information concerning lattice defects can be inferred on a larger scale than that normally accessible by microscopy techniques.
Climb‐Dissociated Dislocations in Monazite at Low Temperature
Authors: Hay R. S.
Published: March 2010

Three types of climb‐dissociated partial dislocations were observed by high‐resolution transmission electron microscopy in monazite (LaPO4) that was indented at room temperature. Two types were found on twin boundaries, and a third in the lattice. Formation mechanisms are discussed. Glide of climb‐dissociated partial dislocations that is allowed by stacking fault migration is considered.
Synthesis of a Visible‐Light Active TiO2−xSx Photocatalyst by Means of Mechanochemical Doping
Authors: Zhang Qiwu , Wang Jun , Yin Shu , Sato Tsugio , Saito Fumio
Published: March 2010

A visible‐light active TiO2−xSx in rutile structure has been synthesized by means of a mechanochemical method. The method is composed of two steps: the first is grinding the mixture of sulfur and TiO2, and the second is calcining the ground sample at 673 K in an inert gas flow. XPS analysis confirms that sulfur has been successfully doped into TiO2. The calcined sample under irradiation of visible light with wave‐length over 510 nm has shown good performance for NO gas destruction, suggesting its high photograph‐reactivity.
Phase Transformation of Nanocrystalline Anatase Powders Induced by Mechanical Activation
Authors: Xiaoyan Pan , Yi Chen , Xueming Ma , Lihui Zhu
Published: March 2010

The microstructural evolution of nanocrystalline anatase TiO2 during high‐energy planetary ball milling was studied. The results show that mechanical activation induces the transformations of nanocrystalline TiO2 from anatase to srilankite and rutile at room temperature and under ambient pressure. As the milling time increases, more anatase powder transforms to the srilankite and rutile phase, and the particle size of the powder decreases. There is no indication of the formation of amorphous phase during ball milling.
Improvement in Wear Resistance of High‐Strength and High‐Toughness Silicon Nitride Modified by Ion Implantation
Authors: Nakamura Naoki , Hirao Kiyoshi , Yamauchi Yukihiko
Published: March 2010

Surface modification by ion implantation has been conducted to improve the tribological properties of a high‐strength and high‐fracture‐toughness unidirectionally aligned silicon nitride (UA‐SN). B+, N+, Si+, and Ti+ ions were implanted into the planes parallel and normal to the grain alignment of the UA‐SN with a fluence of 2 × 1017 ions/cm2 at an energy of 200 keV. The ion implanted UA‐SN showed a dramatic improvement in wear resistance. For example, the specific wear rate of the Si+‐implanted specimen in the direction parallel to the grain alignment was reduced to a value of 3 × 10−10 mm2/N, equal to 1/20 of the unimplanted one. Cross‐sectional transmission electron microscopy indicates the high wear resistance was attributed to the amorphous surface caused by the ion implantation.
Crystallographic Texture Development in Bismuth Sodium Titanate Prepared by Reactive‐Templated Grain Growth Method
Authors: Kimura Toshio , Takahashi Toru , Tani Toshihiko , Saito Yasuyoshi
Published: March 2010

Bi0.5Na0.5TiO3 (BNT) and 0.94Bi0.5Na0.5TiO3·0.06BaTiO3 (BNT–BT) bulk ceramics with extensive 〈100〉 texture were prepared by the reactive‐templated grain growth method, using platelike Bi4Ti3O12 (BIT) particles as templates for BNT. Calcined compacts were composed of matrix grains with random orientation and 〈100〉‐oriented grains transformed from aligned BIT particles, and the texture developed by the growth of oriented grains during sintering. Ceramics with extensive texture were obtained by using the starting mixture containing the maximum concentration of platelike BIT to form the maximum volume fraction of oriented grains.
High‐Frequency Electromagnetic Bandgap Structures via Indirect Solid Freeform Fabrication
Authors: Reilly Christopher J. , Chappell William J. , Halloran John W. , Katehi Linda P. B.
Published: March 2010

The indirect solid freeform fabrication process is used to fabricate low‐loss complex geometry periodic dielectrics for use in the microwave range. Relevant processing details, such as mold fabrication, slurry rheology, curing, and binder burnout, are discussed. Woodpile electromagnetic bandgap structures exhibiting a −40 dB well were shown to be operational at frequencies >110 GHz. Novel designs of planar periodic dielectric resonators with Q= 965 at 33 GHz (Q= ratio of the power stored to power lost in the resonator) were realized in alumina. Metallo‐dielectric filters with low‐insertion loss were also created via ISFF; modeling of these structures using resistor‐inductor‐capacitor‐equivalent circuit analysis was performed to calculate a Q of 645.
Stress Required for Constrained Sintering of a Ceramic‐Filled Glass Composite
Authors: Huang Chiao‐Chan , Jean Jau‐Ho
Published: March 2010

The stress required for complete constrained sintering of a low‐temperature cofirable ceramic‐filled glass composite, i.e., borosilicate glass + alumina, has been investigated under uniaxial constant and cyclic loading. The required uniaxial stress to have complete constrained sintering, i.e., zero strain or strain rate in the perpendicular directions, is in the range of 20–250 kPa, which initially increases with temperature, reaches a maximum at 725°–800°C, and then decreases with increasing temperature. The above measured data exhibit a similar trend to those of required stress and sintering potential calculated using the viscous analogy for the constitutive relationship of a porous sintering compact.
Use of Stress To Produce Highly Oriented Tetragonal Lead Zirconate Titanate (PZT 40/60) Thin Films and Resulting Electrical Properties
Authors: Brennecka Geoff L. , Huebner Wayne , Tuttle Bruce A. , Clem Paul G.
Published: March 2010

Thin films of Pb(Zr0.4TiO.6)O3 produced by chemical solution deposition were used to study the effects of stress from different platinized single‐crystal substrates on film orientation and resulting electrical properties. Films deposited on MgO preferred a (001) orientation due to compressive stress on the film during cooling through the Curie temperature (TC). Films on Al2O3 were under minimal stress at TC, resulting in a mixture of orientations. Those on Si preferred a (111) orientation due to templating from the bottom electrode. Films oriented in the 〈001〉 direction demonstrated lower dielectric constants and higher Pr and −d31 values than (111) films.