bluuebunny/crossref_metadata_2025 huggingface dataset:
PRICE ELASTICITY AND ADVERSE SELECTION IN THE DEMAND FOR SUPPLEMENTARY HEALTH INSURANCE
Authors: MARQUIS M. SUSAN , PHELPS CHARLES E.
Published: January 2010

Probit regression estimates show the effects of the price of insurance, anticipated medical expenditures, and other factors on reported decisions about purchasing hypothetically offered supplementary insurance policies. The demand estimates can characterize how much supplemental insurance would be purchased under different tax policies affecting health insurance purchases. Although eliminating the current tax subsidy to insurance is shown to decrease demand, the results indicate a substantial demand for supplementary insurance even in the absence of present tax incentives. However, our results on adverse selection raise concerns about the potential stability of supplemental insurance markets.
COMPOUND PRICING
Authors: MCGEE JOHN S.
Published: January 2010

Compound pricing makes the price or availability of some goods conditional on the purchase (or non‐purchase) of other goods. Tie‐ins and requirements contracts, two well‐known examples, are analyzed here.

Contrary to some opinion, such practices need not be innocuous or benign. This analysis shows that compound pricing can produce price, output, profit, and welfare results that are practically indistinguishable from those got when a firm increases its monopoly power in more obvious and direct ways. By some standards, the requirements and exclusive dealing contracts analyzed here are predatory.
DETERMINANTS OF REGIONAL MIGRATION BY MANUFACTURING FIRMS
Authors: NAKOSTEEN ROBERT A. , ZIMMER MICHAEL A.
Published: January 2010

Economists have produced a sizable literature examining the role of labor migration in restoring wage and price equilibria among dispersed markets. A much smaller literature addresses another dimension of mobility, regional migration of entrepreneurs and firms. In this study we examine a model of the firm's decision to migrate, utilizing the Duns Market Identifiers data file. The model consists in part of an equation describing the decision to migrate, in order to determine the extent to which measured characteristics of the firm's environment explain firm migration. Additional equations in the model explain particular outcomes of migration: the growth in sales during a fixed interval after a move and the corresponding growth of employment.
Family therapists in trauma‐response teams: bringing systems thinking into interdisciplinary fieldwork
Authors: Mendenhall Tai J. , Berge Jerica M.
Published: January 2010

Attention to the mental health facets of disaster‐preparedness and trauma‐response teams has increased considerably over the past decade. As family therapists take part in these efforts, they bring with them a worldview that adds valuable contributions to the nature in which fieldwork is conducted and the manners in which interdisciplinary teams function on the ground. In this article, we present how systems thinking sensitizes trauma workers to a variety of clinical presentations and biopsychosocial complexities inherent in this work. We describe common clinical‐ and practice‐related challenges, alongside practical strategies for effectively dealing with these challenges. We draw upon our experiences as family therapists trained in the field of trauma, and our work as field responders, supervisors and team leaders across a variety of local and large‐scale disaster events and contexts.
Whither Family Business?
Authors: Schulze William S. , Gedajlovic Eric R.
Published: January 2010

abstract

The family enterprise is capturing increased interest from scholars around the world. Yet research about family business is in its infancy and the diversity of theories and perspectives represented in the developing literature portray a cluttered and conflicted landscape. In the following, we provide background, discuss the state of the field, and place in context the articles that are featured in this special issue. Critical questions facing the field are also addressed.
Generation of transgenic wheat (Triticum aestivum L.) accumulating heterologous endo‐xylanase or ferulic acid esterase in the endosperm
Authors: Harholt Jesper , Bach Inga C. , Lind‐Bouquin Solveig , Nunan Kylie J. , Madrid Susan M. , Brinch‐Pedersen Henrik , Holm Preben B. , Scheller Henrik V.
Published: January 2010

Endo‐xylanase (from Bacillus subtilis) or ferulic acid esterase (from Aspergillus niger) were expressed in wheat under the control of the endosperm‐specific 1DX5 glutenin promoter. Constructs both with and without the endoplasmic reticulum retention signal (Lys‐Asp‐Glu‐Leu) KDEL were used. Transgenic plants were recovered in all four cases but no qualitative differences could be observed whether KDEL was added or not. Endo‐xylanase activity in transgenic grains was increased between two and threefold relative to wild type. The grains were shrivelled and had a 25%–33% decrease in mass. Extensive analysis of the cell walls showed a 10%–15% increase in arabinose to xylose ratio, a 50% increase in the proportion of water‐extractable arabinoxylan, and a shift in the MW of the water‐extractable arabinoxylan from being mainly larger than 85 kD to being between 2 and 85 kD. Ferulic acid esterase‐expressing grains were also shrivelled, and the seed weight was decreased by 20%–50%. No ferulic acid esterase activity could be detected in wild‐type grains whereas ferulic acid esterase activity was detected in transgenic lines. The grain cell walls had 15%–40% increase in water‐unextractable arabinoxylan and a decrease in monomeric ferulic acid between 13% and 34%. In all the plants, the observed changes are consistent with a plant response that serves to minimize the effect of the heterologously expressed enzymes by increasing arabinoxylan biosynthesis and cross‐linking.
Never Say Never? Uncovering the Never‐Unionized in the United States
Authors: Booth Jonathan E. , Budd John W. , Munday Kristen M.
Published: January 2010

This paper analyses individuals who never hold a unionized job and are never represented by a union (‘never‐unionized’). Using 21 waves of the National Longitudinal Survey of Youth 1979 data to track individuals starting at age 15 or 16, we show that by the time workers are 40 or 41 years old, one‐third of them are never‐unionized, and a convex never‐unionization trajectory suggests that most of them will remain never‐unionized. An analysis of the demographic and labour market characteristics of the never‐unionized further suggests two types of never‐unionized workers — those who lack opportunities for obtaining unionized jobs and those who lack the desire to obtain unionized jobs.
Optimal Board Monitoring in Family‐owned Companies: Evidence from Asia
Authors: Chen En‐Te , Nowland John
Published: January 2010

Manuscript Type:Empirical

Research Question/Issue:We propose that high levels of monitoring are not always in the best interests of minority shareholders. In family‐owned companies the optimal level of board monitoring required by minority shareholders is expected to be lower than that of other companies. This is because the relative benefits and costs of monitoring are different in family‐owned companies.

Research Findings/Insights:At moderate levels of board monitoring, we find concave relationships between board monitoring variables and firm performance for family‐owned companies but not for other companies. The optimal level of board monitoring for our sample of Asian family‐owned companies equates to board independence of 38 per cent, separation of the chairman and CEO positions, and establishment of audit and remuneration committees. Additional testing shows that the optimal level of board monitoring is sensitive to the magnitude of the agency conflict between the family group and minority shareholders and the presence of substitute monitoring.

Theoretical/Academic Implications:This study shows that the effect of additional monitoring on agency costs and firm performance differs across firms with different ownership structures.

Practitioner/Policy Implications:For policymakers, the results show that more monitoring is not always in the best interests of minority shareholders. Therefore, it may be inappropriate for regulators to advise all companies to follow the same set of corporate governance guidelines. However, our results also indicate that the board governance practices of family‐owned companies are still well below the identified optimal levels.
The Role of Networks in the Development of UK Migration Policy
Authors: Somerville Will , Goodman Sara Wallace
Published: January 2010

This article examines the ‘policy networks’ that existed between 1997 and 2007 in UK asylum, economic migration and immigrant integration policy. The analysis shows that employers and businesses (together with other state and non-state actors) were part of a tightly organised, ideologically cohesive economic migration ‘policy community’. This policy community was crucial to the development of economic migration policy, in contrast to the development of asylum and integration policies. The central argument of this article is that the mainstream interpretation of UK immigration policy change (that change was driven by an elite-led, powerful executive) is correct in tracing the dynamics of asylum policy development between 1997 and 2007 under New Labour, but wrong for the development of immigration policy as a whole, which was more complex, and where businesses played a key role.
Explaining the Success of Neo-Liberal Populist Parties: The Case of Lijst Dedecker in Belgium
Authors: Pauwels Teun
Published: January 2010

Neo-liberal populist parties, like Forza Italia or Lijst Pim Fortuyn, aim to reverse the trend towards big government and state intervention while at the same time defending the ‘ordinary people’ against an allegedly ‘corrupt elite’. While it is possible to distinguish neo-liberal populism from the populist radical right, it is less clear whether the causes of their electoral successes might be differentiated as well. This article attempts to explain the unexpected breakthrough of the neo-liberal populist Lijst Dedecker (LDD), a new party which gained representation in the Belgian parliament in 2007. It is argued that LDD profited from an electoral opportunity structure – that is, an ideological gap between the mainstream parties, which had converged to the centre, and the Vlaams Belang on the radical right – and the populist appeal from its charismatic leader. Both the populist radical right and neo-liberal populism seem to profit mainly from the same breeding ground.
Making People More Responsible: The Blair Governments' Programme for Changing Citizens' Behaviour
Authors: 6 Perri , Fletcher-Morgan Charlotte , Leyland Kate
Published: January 2010

A distinctive feature of the three Blair New Labour governments' domestic policy was the effort to change citizens' behaviour. Variously explained using such slogans as ‘something for something’, ‘responsibility’ and, in combating antisocial behaviour, ‘respect’, behaviour change was presented by the PM's Strategy Unit as an overarching strategic framework for policy. This included conditionality in welfare to work, health promotion campaigns, a ban on smoking in public places, measures to combat antisocial behaviour and enforce school discipline, home–school contracts, community cohesion and neighbourhood renewal programmes, measures to encourage car sharing and use of public transport, and others to promote domestic waste recycling. This article examines how far the two principal explanatory theories available predict that programme's characteristics. It uses a structured data set on the policy instruments, target groups and content of initiatives undertaken by eight central government spending departments. We find that indeed the strong (more coercive) tools are markedly concentrated on initiatives targeting the poor and low-income working strata. The expectations derived from the two theoretical traditions are not strongly supported.
‘You Feel Sad?’ Emotion Understanding Mediates Effects of Verbal Ability and Mother–Child Mutuality on Prosocial Behaviors: Findings from 2 Years to 4 Years
Authors: Ensor Rosie , Spencer Debra , Hughes Claire
Published: January 2010

Early individual differences in prosocial behaviors are pivotal for children's peer relationships. To investigate the interplay among verbal ability, emotion understanding, and mother–child mutuality as predictors of prosocial behaviors, we observed 102 children at the ages of two, three, and four. All time points included verbal ability and emotion understanding tests and both video‐based and maternal ratings of prosocial behavior. The first two time points also included video‐based ratings of mother–child mutuality. The third time point included teacher ratings of prosocial behavior and an experimental task. Regression analysis demonstrated robust associations between emotion understanding at the age of three and prosocial behavior at the age of four. Path analysis showed that emotion understanding at the age of three mediated associations between verbal ability/mother–child mutuality at the age of two and prosocial behavior at the age of four.
The ‘Scottish’ Approach? The Discursive Construction of a National Police Force
Authors: Gorringe Hugo , Rosie Michael
Published: January 2010

In 2005, the location of the G8 summit meeting in Gleneagles, Scotland, brought the contested boundaries of the state and the nation to the fore. Confronted by the prospect of significant public disorder police forces in Scotland routinely flagged up a ‘Scottish approach to policing’. Drawing on research with key police officers and others we explore the processes through which national identities come to be articulated, contested and acted out in the context of one particular institution: the police. We consider the claim that policing of the summit was ‘Scottish’ and assess the implications of this assertion. Whilst the police have been argued to be integral to the constitution and expression of nation-statehood we highlight the dangers in an uncritical acceptance of police philosophies and also point to the banal ways in which national identity is naturalised.
The Power of Corridors: Connecting Doors, Mobilising Materials, Plotting Openness
Authors: Hurdley Rachel
Published: January 2010

This paper is based on an ethnographic study of corridors in a large university building, originally built to house local government in the early 20th century. By attending to their huge physical presence in the everyday culture of an institution, the paper shows how corridors matter. Too often invoked as iconic, intangible metaphors, the presence of corridors as cultural materials can be forgotten. Conversely, as incidental – or even detrimental – remnants of past design trends, they are perceived parts of a divisive, hierarchical organisation of space. As the open-plan office, indoor street, forum and atrium displace them in a new design for ‘openness’, the study focuses on the mobilisation of corridors in the daily, sometimes momentary re-arrangements of meaning in an organisation. In conclusion, I discuss how the new architecture of ‘openness’ might be reconfigured through mobile understandings of everyday ‘openings’ and ‘closings’.
Efficacy of fixed combinations of acetylsalicyclic acid, acetaminophen and caffeine in the treatment of idiopathic headache: a review
Authors: Anneken K. , Evers S. , Husstedt I. W.
Published: January 2010

Headache is one of the most common reasons for patients to visit their general practitioner. Most of these patients suffer from migraine, tension‐type headache, or a combination of the two; they tend to self‐medicate using over the counter combination headache preparations, particularly acetylsalicyclic acid (ASA) and acetaminophen coformulated with caffeine, which is one of the most commonly used combination analgesics in these patients worldwide. We reviewed studies on the efficacy and safety of this combination. In the treatment of migraine and tension‐type headache, the combination of ASA, acetaminophen, and caffeine has been shown to be more efficacious and superior to monotherapy with the single substances of the combination. According to literature, there is no evidence for higher prevalence of undesirable side‐effects of combination analgesics in comparison to monotherapy.
No mutations in the voltage‐gated NaV1.7 sodium channel α1 subunit gene SCN9A in familial complex regional pain syndrome
Authors: De Rooij A. M. , Gosso M. F. , Alsina‐Sanchis E. , Marinus J. , Van Hilten J. J. , Van Den Maagdenberg A. M. J. M.
Published: January 2010

Background:  Mutations in the voltage‐gated NaV1.7 Na+ channel α1 gene SCN9A have been linked to pain disorders, such as inherited primary erythromelalgia and paroxysmal extreme pain disorder. Both show clinical overlap with complex regional pain syndrome (CRPS), a condition that is characterized by pain in association with combinations of vasomotor, sudomotor, sensory, and motor disturbances. Therefore, we here investigated the involvement of the SCN9A gene in familial CRPS.

Methods:  We performed a mutation analysis of the SCN9A gene in four index cases of families with CRPS. All 26 coding exons and adjacent sequences of the SCN9A gene were analyzed for mutations using direct sequencing analysis.

Results:  No causal gene mutations were identified in the SCN9A gene in any of the patients.

Conclusions:  Despite the fact that the SCN9A gene is an excellent candidate, we did not find evidence that it plays a major role in familial CRPS.
Predicted impact of climate change on threatened terrestrial vertebrates in central Spain highlights differences between endotherms and ectotherms
Authors: Aragón P. , Rodríguez M. A. , Olalla‐Tárraga M. A. , Lobo J. M.
Published: January 2010

Climate change can induce shifts in species ranges. Of special interest are range shifts in regions with a conflict of interest between land use and the conservation of threatened species. Here we focus on the 94 threatened terrestrial vertebrates occurring in the Madrid region (Central Spain) and model their distributions using data for the whole peninsular Spain to evaluate which vertebrate groups are likely to be more sensitive to climatic change. First, we generated predictive models to quantify the extent to which species distributions are explained by current climate. We then extrapolated the models temporally to predict the effects of two climate‐change scenarios on species distributions. We also examined the impact on a recently proposed reserve relative to other interconnected zones with lower protection status but categorized as Areas of Community Importance by the European Union. The variation explained by climatic predictors was greater in ectotherms. The change in species composition differed between the proposed reserve and the other protected areas. Endothermic and ectothermic vertebrates had different patterns of changes in species composition but those of ectotherms matched with temperature departures predicted by climate change. Our results, together with the limited dispersal capacity of herptiles, suggest that trade‐offs between different design criteria accounting for animal group differences are necessary for reserve selection.
Risk factors and prodromal eating pathology
Authors: Stice Eric , Ng Janet , Shaw Heather
Published: January 2010

Prospective studies have identified factors that increase risk for eating pathology onset, including perceived pressure for thinness, thin‐ideal internalization, body dissatisfaction, dietary restraint, and negative affect. Research also suggests that body dissatisfaction and dietary restraint may constitute prodromal stages of the development of eating disorders. Prevention trials indicate that interventions that reduce pressure to be thin, thin‐ideal internalization, body dissatisfaction, and negative affect significantly reduce eating disorder symptoms. Further, there is evidence that selective prevention programs that target young women at elevated risk for eating pathology by virtue of thin‐ideal internalization, body dissatisfaction, and negative affect produce significant larger intervention effects than do universal programs offered to unselected populations. Thus, research on risk factors and prodromal stages of eating pathology has assisted in the design of efficacious prevention programs and the identification of high‐risk individuals to target with these interventions; additional research in this area may lead to even more effective prevention programs.
On the trail of 007: media pilgrimages into the world of James Bond
Authors: Reijnders Stijn
Published: January 2010

Visiting the settings of popular films and TV series has become a growing niche in the tourist market; however, little is known about what makes these visits so appealing. The present research used the case of James Bond ‘pilgrims’ to explore this issue. Twenty‐three interviews were conducted with James Bond fans who had visited one or more Bond film locations in recent years. These interviews indicate that the ‘media pilgrimage’ into the world of Bond contains playful as well as serious elements. By tracing the world of Bond and temporarily becoming part of this liminal landscape, fans create the opportunity to embody and perform an imagined masculinity. On a theoretical level, this paper contributes to the literature on media pilgrimages, by showing how the symbolic boundary between inside and outside the media is tightly interwoven with other power configurations – in this case, patriarchal notions of masculinity.
Pupils or prisoners? Institutional geographies and internal exclusion in UK secondary schools
Authors: Barker John , Alldred Pam , Watts Mike , Dodman Hilary
Published: January 2010

A growing interest in the geographies of schooling has led to an exploration of a variety of school spaces. An increasing number of secondary schools offer internal fixed‐term exclusions so that temporary removal from school is not seen as ‘time off’ for students. This particular strategy has led to the creation of a new type of space in schools. Drawing upon research undertaken in a London secondary school, this paper explores the geography of these new secluded spaces. We highlight that the configuration of physical space in Seclusion Units and the regulation of spatial practices create highly controlled and segregated spaces of punishment. We explore the powerful transformative effects of these spaces to change students' behaviour, social interaction and attitudes to learning. However, rather than simply creating docile subjects, we recognise that domination is never complete and we explore the extent and the limit of student resistance to the discipline and control of the Seclusion Unit.
Mapping the hieroglyphic self: spiritual geometry in the letters of John Winthrop, Jr, and Edward Howes (1627–1640)
Authors: Shrieves Katherine
Published: January 2010

This paper examines letters written by Edward Howes, a London mathematician and clerk, to his friend John Winthrop, Jr, an early American colonist with an interest in natural philosophy. In this transatlantic correspondence, Howes uses alchemical transformation as a controlling metaphor for ‘perfection’ that is both private and public, personal and global. These letters envision Winthrop and Howes as participants in a unique historical moment, with the capacity to attain a divine ‘Centre of Truth’ within their own perfected souls, to forge a uniquely intimate friendship that transcends geographic boundaries, and to aid in the creation of a godly community in New England. This paper argues for an equation between Howes's notion of the perfected self and Protestant election, in which spiritually elite American colonists and ‘elect’ readers of alchemical texts experience a similarly special relationship with the divine. Moreover, Howes's rhetoric suggests a connection between the hope for individual and societal perfection and Winthrop's quest to find the Northwest Passage, envisioned as a channel facilitating a diffusion of Christ's spirit throughout the world and a transcendent union of East and West.
Predictability in Consumption Growth and Equity Returns: A Bayesian Investigation
Authors: Paseka Alex , Theocharides George
Published: January 2010

We use a Bayesian method to estimate a consumption‐based asset pricing model featuring long‐run risks. Although the model is generally consistent with consumption and dividend growth moments in annual data, the conditional mean of consumption growth (a latent process) is not persistent enough to satisfy the restriction that the price‐dividend ratio be an affine function of the latent process. The model also requires relatively high intertemporal elasticity of substitution to match the low volatility of the risk‐free return. These two restrictions lead to the equity volatility puzzle. The model accounts for only 50% of the total variation in asset returns.
ZrB2–SiC Oxidation Protective Coating on C/C Composites Prepared by Vapor Silicon Infiltration Process
Authors: Zhou Haijun , Gao Le , Wang Zhen , Dong Shaoming
Published: January 2010

ZrB2–SiC coating on C/C composites was prepared through vapor silicon infiltration process. The coated C/C composites showed excellent oxidation performance at 1500°C. Isothermal oxidation results showed that there was weight gain accompanied in the whole oxidation process and no evidence of oxidation of C/C composite substrate was observed. The thickness of coating increased from 120 μm to about 200 μm after oxidizing at 1500°C. Three distinct layers could be observed in the coating, namely, outer SiO2‐rich layer, middle ZrB2‐rich layer, and inner SiC‐rich layer. ZrB2particles were coarsened after oxidation.
Microwave Dielectric Properties of Low‐Temperature Sinterable BaCe2(MoO4)4 Ceramics
Authors: James Nijesh Kunnamkuzhakal , Ratheesh Ravendran
Published: January 2010

Low‐temperature sinterable BaCe2(MoO4)4 ceramics were prepared through solid‐state ceramic route. X‐ray diffraction, laser Raman spectroscopy and scanning electron microscopy techniques have been used to investigate the structure and microstructure of BaCe2(MoO4)4 ceramics. The laser Raman study reveals distorted MoO42− tetrahedral networks in the unit cell of the BaCe2(MoO4)4 ceramics. The BaCe2(MoO4)4 exhibits a dielectric constant of 12.3, an unloaded quality factor of 3320, and a temperature coefficient of resonant frequency of −37 ppm/°C.
Effect of Applied Stress on IR transmission of Spark Plasma‐Sintered Alumina
Authors: Chakravarty Dibyendu , Sundararajan G.
Published: January 2010

The effect of applied stress on IR transmittance of nanocrystalline alumina prepared by spark plasma sintering was evaluated. Transparent alumina with maximum transmittance >80% was obtained over the entire mid‐IR wavelength range of 3–5 μm by applying a high stress of 275 MPa at 1150°C using specially designed high‐strength compound dies. The transmittance observed was similar to previous reports at identical wavelengths, but at a lower sintering temperature. The transparent samples have an average grain size of 0.3 μm and a hardness of 23 GPa. At lower stresses and sintering temperatures, transmittance reduced drastically due to remnant pores in the matrix as observed from the microstructural analysis. The effect of porosity was found to be critical in developing transparency as even a marginal decrease in porosity led to substantial increase in transmittance.
Effect of Oxygen Partial Pressure During Firing on the High AC Field Response of BaTiO3 Dielectrics
Authors: Fujii Ichiro , Ugorek Michael , Han Yisong , Trolier‐McKinstry Susan
Published: January 2010

The effect of oxygen partial pressure during firing on the high field dielectric response of formulated and undoped BaTiO3 ceramics was investigated. For formulated ceramics, the dielectric constant of both oxygen‐ and air‐fired samples increased almost linearly with the amplitude of the ac‐driving field. Formulated BaTiO3 samples sintered in a reducing atmosphere produced a sublinear increase in the permittivity with the ac field amplitude. For undoped BaTiO3 ceramics, the dielectric constant increased sublinearly over a wide range of oxygen partial pressures during firing. It is proposed for the formulated ceramics that the dopant‐oxygen vacancy defect dipoles in the shell region accounted for the curvature in the field dependence of the permittivity. These defects appear to add a concentration of weak pinning centers to the potential energy profile through which domain walls move.
Optical Properties of Heavily Al‐Doped Single‐Crystal Si3N4Nanobelts
Authors: Gao Fengmei , Wang Yansong , Zhang Ligong , Yang Weiyou , An Linan
Published: January 2010

The optical properties of heavily Al‐doped single‐crystal Si3N4nanobelts are investigated by measuring their absorption, photoluminescence, and photoluminescence excitation spectra. The results suggest that the doped Si3N4exhibit two absorptions at 2.5 and 4.2 eV, instead of absorption at 5.0 eV in the pure Si3N4. The doped nanobelts show light emissions in a range of 1.4 to 3.6 eV, which is red‐shifted as compared with that of pure Si3N4nanobelts. These results are ascribed to the unique doping mechanism of Al, which generates two types of defects.
A Viable Route for Dense TiO2with a Low Microwave Dielectric Loss
Authors: Zhang Lanlin , Shqau Krenar , Verweij Henk , Mumcu Gokhan , Sertel Kubilay , Volakis John L.
Published: January 2010

Dense, high‐purity TiO2was prepared from commercially available powders. These powders were deagglomerated, colloidally stabilized in aqueous NH3, followed by screening to remove residual agglomerates. Homogeneous compacts were formed using colloidal‐filtration followed by sintering. TiO2with >99.5% density and 400 MPa flexural strength was obtained at a sintering temperature as low as 1000°C. The dielectric loss of this TiO2was 1.4 × 10−4at 6.4 GHz at room temperature. This implied that the product of the quality factor and frequency, (Q×f )=f/tan δ, was 46 000 GHz, ∼7.6 times higher than 6000 GHz (Q<2000 at 3 GHz) reported previously. This high‐quality factor is attributed to the low sintering temperature as well as a homogeneous dense microstructure with 2.2 μm grain size. The process described can be applied to realize complex TiO2structures in new microwave antenna concepts, that require components with a high dielectric constant and low dielectric loss.
(K,Na)NbO3‐Based Ceramics for Piezoelectric “Hard”Lead‐Free Materials
Authors: Lim Jong Bong , Zhang Shujun , Jeon Jae‐Ho , Shrout Thomas R.
Published: January 2010

Lead‐free piezoelectric ceramics (K0.45Na0.55)NbO3 (KNN) modified by K4CuNb8O23 (KCN) were synthesized using conventional ceramic processing. All the ceramics possessed the perovskite structure with orthorhombic symmetry. Results revealed that the addition of KCN was effective in enhancing the density of KNN. The addition of KCN was found to slightly decrease To–t and Tc. The coercive field (Ec) was found to maintain the same value by the addition of KCN while the internal bias (Ei) sharply increased to 4 kV/cm with 0.5 mol% KCN. The low migration rate of defect dipoles was correlated with the build‐up of Ei, which was responsible for the stabilization of the domain wall and the improvement of Qm. Therefore, KNN–KCN0.5 exhibited excellent piezoelectric properties of d33 (100 pC/N), kp (33%), and Qm (1500), making them promising candidates for applications requiring hard piezoelectrics.
Synthesis of Silicon Nitride Fibers by the Carbothermal Reduction and Nitridation of Rice Husk Ash
Authors: Pavarajarn Varong , Precharyutasin Ruttairat , Praserthdam Piyasan
Published: January 2010

Silicon nitride (Si3N4), a high‐temperature structural ceramic, was synthesized from low‐cost rice husk ash (RHA) via carbothermal reduction and nitridation at temperature in the range of 1400°–1470°C for 3–10 h. Three forms of Si3N4 product, i.e., powder mixed with the residual RHA, a layer of single‐crystalline whiskers formed on top of the RHA bed, and long polycrystalline fibers formed outside the cavity of the sample holder, were obtained. Both whisker and fiber products could be easily separated from the remaining RHA. Extensive characterizations by X‐ray diffraction, X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy were conducted to investigate the reaction mechanism. Silicon nitride in both whisker and long fiber forms are suggested to grow via the vapor–solid mechanism, in which silicon monoxide (SiO) vapor is the reaction intermediate. The single‐crystalline whiskers are formed directly from the gas phase, but the product in long fiber form grows through the formation of an amorphous intermediate. The condition, which enhances the production of SiO vapor, such as an increased temperature or increased flow rate of the supplied gas, results in significant increase in the yield of both fibrous products, especially in the sample holder placed downstream.
Synthesis of Ultra‐Fine Hafnium Carbide Powder and its Pressureless Sintering
Authors: Liu Ji‐Xuan , Kan Yan‐Mei , Zhang Guo‐Jun
Published: January 2010

Ultra‐fine HfC powders with particle sizes of 380 or 225 nm were synthesized by carbothermal reduction of HfO2 with graphite or carbon black, respectively. The investigation of the process indicated that a vacuum level as high as 5 Pa was appropriate for decreasing the reaction temperature and consequently limiting the particle growth of HfO2 reactant. Type and size distribution of carbon sources demonstrated an obvious effect on the particle size of the HfC powders obtained. A model was proposed to explain this phenomenon. Carbon black with a characteristic particle size of 42 nm resulted in a HfC powder with a median particle size of 225 nm. Compared with the reported values in the literature, the synthesized HfC powder exhibited better sinterability than the commercial HfC powder. Using the synthesized powder, monolithic HfC ceramics pressureless sintered at 2400°C reached a relative density of 98.4% and an average grain size of about 4 μm.
Low‐Temperature Sintering of Li‐Modified (K, Na)NbO3 Lead‐Free Ceramics: Sintering Behavior, Microstructure, and Electrical Properties
Authors: Wang Ke , Li Jing‐Feng
Published: January 2010

With the assistance of excess Na2O additives, LiNbO3‐doped (K, Na)NbO3 lead‐free piezoceramics were successfully prepared by conventional sintering at a temperature as low as 950°C. Shrinkage curve measurement and micrograph observation elucidate that the nature of the densification behavior at 950°C is liquid phase sintering, during which the liquid phase penetrated between initial small particles and large quadrate grains of 20–40 μm formed in the solution–precipitation process. Although the density and grain size show inappreciable changes during the final stage of the coalescence process, the piezoelectric properties of the sintered samples are greatly influenced by the soaking time, depending on the optimization of which the piezoelectric constant d33 and the planar mode of the electromechanical coupling factor kp reached 280 pC/N and 48.3%, respectively. The present study revealed that good piezoelectric properties can be obtained in the Li‐doped KNN ceramics even by normal sintering at a reduced temperature (950°C).
Piezoelectric and Ferroelectric Properties of Li‐Doped (Bi0.5Na0.5)TiO3–(Bi0.5K0.5)TiO3–BaTiO3 Lead‐Free Piezoelectric Ceramics
Authors: Dai Ye‐Jing , Zhang Shujun , Shrout Thomas R. , Zhang Xiao‐Wen
Published: January 2010

The piezoelectric and ferroelectric properties of 0.852[Bi0.5(Na(1−x)Lix)0.5]TiO3–0.110(Bi0.5K0.5)TiO3–0.038BaTiO3 (x=0, 0.02, 0.05, 0.10, 0.15, and 0.30, abbreviated as BNKLBTx) lead‐free piezoelectric ceramics were prepared by conventional ceramic processing. X‐ray diffraction on the samples revealed that Li+ ions diffused into the Bi0.5Na0.5TiO3 lattices (A‐site) and formed a solid solution with a single perovskite structure. All the samples could be sintered at 1160°–1180°C, with the density being on the order of >95% of the theoretical. The ceramics with x=0.10 exhibited the highest properties, with the piezoelectric coefficient being on the order of d33=235 pC/N, while the electromechanical coupling factors were found to be kp=0.30 and kt=0.45, respectively. The dielectric, pyroelectric, electromechanical, and ferroelectric behaviors were investigated as a function of temperature. It was found that the depolarization temperature Td showed a strong dependence on the content of Li+ addition, shifting to a lower temperature with increasing Li+ dopant.
Synthesis and Drug Delivery Property of Calcium Phosphate Cement with Special Crystal Morphology
Authors: Yu Tao , Ye Jiandong , Gao Chengying , Yu Long , Wang Yingjun
Published: January 2010

In this work, the drug‐release behavior was achieved by controlling the hydration crystal morphology formed during the setting reaction of cement. Two kinds of calcium phosphate cement (CPC) matrix with different and typical crystal morphology were prepared, and the cumulative percentage of gentamicin sulfate (GS) released from the hydrated bone cements was characterized in vitro. The relation between the cumulative percentage and the releasing time showed that both systems exhibited a reasonable low initial GS burst (about 20% and 30% for CPC‐1 and CPC‐2 in about 4 days, respectively) and sustained release behavior with different drug‐release rates. CPC‐1 and CPC‐2 showed a different drug‐releasing ratio after 30 days: 40% and 80%, respectively.
Crystal Structures and Optical Properties of Transparent Ceramics Based on Complex Perovskite Ba(M4+,B12+,B25+)O3 (M4+=Ti, Sn, Zr, Hf; B12+=Mg, Zn; B25+=Ta, Nb)
Authors: Kintaka Yuji , Kuretake Satoshi , Tanaka Nobuhiko , Kageyama Keisuke , Takagi Hiroshi
Published: January 2010

We investigated the crystal structures and optical properties of Ba(M,Mg,Ta)O3, Ba(M,Zn,Ta)O3, and Ba(M,Mg,Nb)O3 (M=Ti, Sn, Zr, and Hf) transparent ceramics. Tetravalent cation substitution resulted in a reduction in the 1:2 order structure of the B‐site of the parent perovskites; this in turn led to an increase in the transmittance of the ceramics. There was an increase in the refractive index of Ba(Mg1/3Ta2/3)O3 due to Ti, Zr, and Hf substitution at the B‐site; the refractive index was particularly high in the case of Ti substitution. Furthermore, Ti substitution resulted in a significant decrease in the Abbe number of Ba(Mg1/3Ta2/3)O3. The refractive index of the perovskites was calculated with high accuracy using the Gladstone–Dale relation. We hypothesize that the Abbe number of perovskites is dependent on its band‐gap energy.
Phase Relation and Microwave Dielectric Properties of (Zn1−xCox)Ta2O6System
Authors: Huang Cheng‐Liang , Chen Jhih‐Yong
Published: January 2010

High‐dielectric constant and low‐loss ceramics in the (Zn1−xCox)Ta2O6ceramics have been prepared by the conventional mixed oxide route and their microwave dielectric properties have been investigated. A phase change or crossover from ZnTa2O6to CoTa2O6occurred atx=0.07 and was completed atx=0.11 and it tends to form a continuous solid solution elsewhere. An over‐sintered specimen would lead to a slight decrease in the density resulting in a decline of the dielectric constant and theQ×fvalue. The specimen withx=0.05 possessed an excellent combination of microwave dielectric properties: ɛr∼38.47,Q×f∼112 000 GHz, and τf∼11.2 ppm/°C. It is proposed as a candidate material for today's 3G passive components and especially small‐sized GPS patch antennas.
Enhanced Blue Emission from Transparent Oxyfluoride Glass–Ceramics Containing Pr3+:BaF2Nanocrystals
Authors: Biswas Kaushik , Sontakke Atul D. , Ghosh Jiten , Annapurna Kalyandurg
Published: January 2010

Transparent glass–ceramics containing Pr3+:BaF2nanocrystals in the chemical composition of SiO2–BaF2–K2CO3–La2O3–Sb2O3oxyfluoride glass systems have been prepared from melt quenching and with a subsequent heat‐treatment method. The luminescence and structural properties of these materials have been evaluated and the results are reported. Rietveld analysis of X‐ray diffraction patterns and investigation of transmission electron microscopy confirmed the presence of BaF2nanocrystals dispersed in the heat‐treated glass matrices. Measured UV‐Vis‐NIR absorption spectra exhibited nine bands of the transitions3H4→3P2, (1I6,3P1),3P0,1D2,1G4,3F3,3F2,3H6, and3H5from all the samples with nondegenerated1I6and3P1levels in the glass–ceramics. The photoluminescence spectra show an enhancement in the intensities upon ceramization, indicating the incorporation of Pr3+ions into BaF2nanocrystals that possess a low phonon energy (346 cm−1). This has further been corroborated from the observation of a significant threefold increase in the relative intensity ratio of blue (3P0→3H4) to red (1D2→3H4,3P0→3H6) emissions from glass–ceramics compared with the glass. This is due to a significant decrease of multiphonon nonradiative relaxation from the3P0to the1D2level of Pr3+in glass–ceramics. Time‐resolved spectra exhibit3P0‐level decays faster than the1D2level.
The Route for Synthesis of Agglomeration‐Free Barium Strontium Titanate Nanoparticles Using Ultrasonic Spray Nozzle System
Authors: Yoon Songhak , Kim Kyuyeon , Baik Sunggi
Published: January 2010

Barium strontium titanate nanoparticles of spherical morphology and variable sizes could be synthesized by alkoxide–hydroxide sol‐precipitation method, adopting an ultrasonic spray nozzle system. In the warm aqueous solution of barium and/or strontium hydroxide, a diluted solution of titanium isopropoxide (TIIP) in isopropanol was introduced as fine droplets produced by passing the solution through the ultrasonic nozzle. Phase‐pure nanocrystals were produced. They were spherical, agglomeration‐free, and fairly narrow in particle‐size distribution. The average particle size can be controlled by changing the precursor concentration. When the TIIP concentration was increased above a certain critical value, a further increase in the particle size was interrupted as many doublets and triplets of particles were formed. The selection of spraying the precursor solution was critical for obtaining monodispersity, and it is found that confining the TIIP is crucial to obtain agglomeration‐free nanoparticles.
Nanodomain Structure of Carbon‐Rich Silicon Carbonitride Polymer‐Derived Ceramics
Authors: Mera Gabriela , Tamayo Aitana , Nguyen Hong , Sen Sabyasachi , Riedel Ralf
Published: January 2010

The presence of nanodomains in polymer‐derived ceramics constitutes one of the most intriguing features of this class of materials. In the present work, the nanostructure of novel carbon‐rich silicon carbonitride (SiCN) ceramics synthesized via thermolysis of poly(methylphenylsilylcarbodiimide), –[Ph(CH3) Si‐NCN]n–, at 1300°, 1500°, 1700°, and 2000°C is investigated by micro‐Raman spectroscopy, X‐ray powder diffractometry, and small‐angle X‐ray scattering (SAXS). The structural information obtained from these experimental methods is combined together with theoretical modeling of the SAXS data to obtain a detailed model of the temperature‐dependent evolution of nanodomains comprised of free carbon, SiC, and Si3N4in SiCN‐based ceramics.
The Thermodynamic Significance of Order Parameters During Glass Relaxation
Authors: Araujo Roger J. , Mauro John C.
Published: January 2010

The thermodynamic state of a glass is often described in terms of a number of order parameters, each of which evolves toward its equilibrium value during glass relaxation. The problem comes in identifying these order parameters and determining their physical significance. The authors argue that the order parameters in a glass can be defined in terms of a set of configurational temperatures, each corresponding to a particular mode of energy storage. The evolution of glass properties can then be calculated using a coupled set of rate equations describing the relaxation of the configurational temperatures toward their equilibrium values, viz., the reservoir temperature. The authors illustrate the concept of configurational temperatures by considering the free energy of mixing in alkali borate and silicate glasses.
Reaction Synthesis and Pressureless Sintering of Cr2AlC Powder
Authors: Panigrahi Bharat Bhooshan , Chu Min‐Cheol , Kim Yong‐Il , Cho Seong‐Jai , Gracio Jose J.
Published: January 2010

This work was aimed to produce Cr2AlC powder through two‐step reactions and to sinter it under a pressureless condition, and the related synthesis and sintering mechanisms were evaluated. Cr2AlC powder of ∼9 μm in size was produced using CrCx and Al powders and sintered to a relative density of ∼95.5%. The sintering was characterized by an activation energy of 267±23 kJ/mol and the mixed mode of sintering comprised of the surface diffusion mechanism and the transient liquid‐phase sintering caused by melting of Al–Cr intermetallic impurities. The sintered sample exhibited Vickers hardness of 3.4 GPa.
Preparation and Characterization of a New Microwave Dielectric Ceramic Ba4ZnTi11O27
Authors: Zhou Huanfu , Chen Xiuli , Fang Liang , Hu Changzheng , Wang Hong
Published: January 2010

Preparation, sintering behavior, and microwave dielectric properties of Ba4ZnTi11O27 ceramic were investigated. The single‐phase Ba4ZnTi11O27 ceramic can be well densified in the temperature range from 1175° to 1250°C with a relative density about 97%. X‐ray diffraction data show that Ba4ZnTi11O27 has a monoclinic structure (C2/m), with lattice parameters of a=19.81549 Å, b=11.43072 Å, and c=9.91129 Å when the sintering temperature is 1200°C. Pure monoclinic Ba4ZnTi11O27 ceramic sintered at 1200°C for 2 h exhibits good microwave dielectric properties with a permittivity about 36.8, Q×f value about 16 460 GHz, and temperature coefficient of resonant frequency about 17.2 ppm/°C. The addition of BaCu(B2O5) can effectively lower the sintering temperature from 1200° to 925°C and does not induce degradation of the microwave dielectric properties. Obviously, the Ba4ZnTi11O27 ceramic can be applied to microwave low‐temperature cofired ceramics devices.
Synthesis and Crystal Structure Characterization of Silicate Apatite Sr2Y8(SiO4)6O2
Authors: Shen Yiqiang , Tok Alfred , Dong Zhili
Published: January 2010

Pure Sr2Y8(SiO4)6O2 powders were obtained after a solid‐state reaction at 1400 °C for 6 h using the nanosized Y2O3, commercial SrCO3, and silica gel. The nanosized Y2O3 powder was synthesized by a precipitation method using Y(NO3)3 and NH4HCO3, followed by a heat treatment. The crystal structure of Sr2Y8(SiO4)6O2 was characterized by powder X‐ray diffraction, Rietveld refinement, and high‐resolution transmission electron microscopy. Results show that Sr2Y8(SiO4)6O2 has a typical apatite‐type structure AI4AII6(BO4)6X2 in the P63/m space group. The lattice parameters are a=9.3884(6) Å and c=6.8657(4) Å. There are two special sites, AI (4f) and AII (6h), in the apatite structure. The AII sites are fully occupied by Y, while the AI sites are randomly filled by Y and Sr atoms. The crystallographic data obtained from Sr2Y8(SiO4)6O2 and other silicate oxyapatites are compared and summarized.