bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategic Alliances: State‐Business Relations in Mexico Under Neo‐Liberalism and Crisis
Authors: KLEINBERG REMONDA BENSABAT
Published: April 2005

Abstract
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This paper examines how neoliberal policies implemented under Carlos Salinas Gortari (1988–1994) changed the nature of state‐private sector relations in Mexico. The paper attempts to show how Mexico's entry into the North American Free Trade Agreement (NAFTA) solidified a strategic alliance between the state and business. The drastic peso devaluation of December 1994 and the ensuing economic crisis however, threatened to shatter the very foundation of the new alliance with the private sector. This paper thus, explores how the Ernesto Zedillo regime (1994–2000) addressed the expectations of the capital class and strengthened its transparent ties with the private sector. The paper argues that given the nature of the more transparent strategic alliance formed under the Salinas administration, big business continues to be brought into the policy making process, and that in fact, Zedillo continues to intervene on the side of business.
Representing the state? School and teacher in post‐Sendero Peru⋆
Authors: Wilson Fiona
Published: April 2005

The school and the teacher give rise to different images and sets of meaning. Locating schools is a technique of government and teachers are supposed to act as mediators between state and society. But teachers are also local intellectuals and have actively engaged in discourses of dissent and challenges to the state. This article explores the changing identity, situation and representation of provincial schoolteachers in post‐conflict Andean Peru. It draws on material from Tarma province to debate the extent to which the former racist “social order”, upheld by school and teacher, has been destabilised and superseded.
Nationalism and democratic construction: the origins of Argentina and Uruguay's political cultures in comparative perspective
Authors: Spektorowski Alberto
Published: April 2005

The article focuses on the different effects the formation of national identity had on the development of political democracy in Uruguay and Argentina. Uruguay's process of state building after the civil wars relied on political consensus regarding the rules of the game: the concept of political democracy became an integral part of Uruguay's collective identity. In Argentina, political elites after the civil wars divided on the question of national identity and the substance of political democracy. Uruguay's political identity as apartidocracia[rule by parties] is not a guarantee against authoritarianism, but the country's democratic political culture is resilient, permeating even the armed forces. In Argentina, the exclusionist character of the political process invites authoritarianism, whether of the liberal or populist‐democratic variety. This article focuses, first, on the different models of collective identity that developed after independence; second, on the distinct roles played by the two hegemonic parties in each nation ‐ the Colorados under Batlle and the Radicals under Yrigoyen; and finally, on the authoritarian periods both countries experienced in the 1930s.
Carlos Saúl Menem: variations on the theme of populism
Authors: Szusterman Celia
Published: April 2005

The labels neopopulist and/or neoliberal have been attached to Latin American political leaders in an effort to understand the post‐transition to democracy experiences. This article examines the appropriateness of such labels in the Argentine context in the 1990s. It is argued that describing Carlos Menem as either neopopulist or neoliberal obscures rather than illuminates the vicissitudes along the path to establishing the institutions of liberal democracy, a commitment the Argentine electorate made in 1983. An old‐style populist at heart, Menem's pragmatic embrace of the neoliberal zeitgeist can only be understood in the context of the social, political and economic upheavals of the 1980s in Argentina.
The rise and fall and rise of populism in Venezuela
Authors: Davilaa Luis Ricardo
Published: April 2005

The article seeks to outline the main elements through which a populist political order was built in Venezuela. It will be done, first by looking at the golden years a of Venezuelan populism (1945–1948). It will be argued that the constitution of populist politics meant: an appeal to the people, the articulation of new social relations and constitution of new political identities. Then it will turn to the latter Pérez and Caldera showing the basic schemes of their governments. They sought to reconstitute politics and reshape political identities in a new populist way. The arrival of Chávez at power and the first months of his government are also analysed.
Culturing identities, the state, and national consciousness in late nineteenth‐century western Guatemala1⋆
Authors: Watanabe John M.
Published: April 2005

This paper examines the procedural culture that shaped ethnic and national identities in late nineteenth‐century western Guatemala. Rooted in face‐to‐face encounters between departmentaljefes políticos(departmental governors) and local Maya communities, this procedural culture emerged from routines of governance such as annual municipal inspections, ethnic struggles for municipal control, and local efforts to title community lands that led Maya and state officials to develop contrasting understandings of each other and their relations. Far from precipitating a national identity of mutual belonging, state formation here intensified the racism and political violence that would rend Guatemala during the century to come.
The Chilean presidential elections of 1999–2000 and democratic consolidation
Authors: Angell Alan , Pollack Benny
Published: April 2005

This article examines the campaign and the outcome of the presidential elections held in 1999–2000 in Chile. It argues that the election marks a crucial phase in the consolidation of democracy in Chile. It can be seen as the first “normal” election since the return to democracy in 1990. It was unusually competitive and the result was in doubt until the second round vote. The election was notable for its emphasis on the future. Issues of the past were largely ignored ‐ as was the position of General Pinochet in London. The campaign of the Right was based upon an above‐party appeal while that of the ruling coalition relied on the traditional weight of parties in Chile. The result can be seen as an endorsement of the policies of the Concertacion government, but it also represented a resurgence of the Right. The victorious candidate, Ricardo Lagos, has stressed his commitment to social justice and to equity ‐ but he faces the problem of a governing coalition with internal differences still to be resolved, and a Right better placed to be a formidable opposition.
A decade of electoral democracy: continuity, change and crisis in Paraguay⋆
Authors: Lambert Peter
Published: April 2005

In 1989 President Stroessner was overthrown after almost 35 years in power. This led to a process of transition over the following decade which included elections at presidential, congressional, and municipal levels, as well as a democratic constitution, which guaranteed full political and civil liberties. However, the transition has been complicated by the continued prominence of the same political and military forces that supported Stroessner, and that have proved reluctant to withdraw from power. As a result, instead of representing a complete break with an authoritarian past, the transition has combined elements of continuity and change. This has led to a conservative and faltering transition, characterised by frequent political crises and the lack of socio‐economic reform. This article analyses the major structural and institutional obstacles to the consolidation of democracy in Paraguay. It then brings the reader up to date, by examining the events of 1998/1999, a period in which Paraguay's transition came under the greatest threat, and which revealed both its greatest strengths and weaknesses.
Patronage and empowerment in the central Amazon
Authors: Hoefle Scott William
Published: April 2005

The shift from modern to post‐modern politics in the Central Amazon is critically evaluated. While considerable empowerment of previously marginalised. Amerindians, rubber tapers and frontier peasants has occurred, patronage networks remain top down in their decision‐making process, significant horizontal political mobilisation between different social actors has not emerged and grassroots political organisation has been stymied by authoritarian politics at the state level. Consequently, as empowerment is supposed to lie at the heart of building sustainable livelihoods in the Amazon, by this line of logic, the future of the region would seem to be seriously compromised.
Rights to land and resources in Argentina's Alerces National Park
Authors: Aagesen David
Published: April 2005

Alerces National Park, created in 1937 to protect temperate forest ecosystems in Argentina's southern Andes, contains 42 families within its borders. Grazing is the principal livelihood strategy of most park inhabitants. Domesticated animals, however, are not compatible with the conservation objectives of park authorities, who are promoting tourism as a sustainable alternative to livestock. Park inhabitants are less enthusiastic about tourism. They lack a meaningful role in negotiating rights to land and resources, and they have been marginalised from conservation planning. This could be alleviated by titling parts of Alerces National Park to park inhabitants and providing them with shared management responsibilities.
Does the Market Value Financial Expertise on Audit Committees of Boards of Directors?
Authors: DEFOND MARK L. , HANN REBECCA N. , HU XUESONG
Published: April 2005

We examine three‐day cumulative abnormal returns around the announcement of 702 newly appointed outside directors assigned to audit committees during a period before implementation of the Sarbanes‐Oxley Act (SOX). Motivated by the SOX requirement that public companies disclose whether they have a financial expert on their audit committee, we test whether the market reacts favorably to the appointment of directors with financial expertise to the audit committee. In addition, because it is controversial whether SOX should define financial experts narrowly to include primarily accounting financial experts (as initially proposed) or more broadly to include nonaccounting financial experts (as ultimately passed), we separately examine appointments of each type of expert. We find a positive market reaction to the appointment of accounting financial experts assigned to audit committees but no reaction to nonaccounting financial experts assigned to audit committees, consistent with accounting‐based financial skills, but not broader financial skills, improving the audit committee's ability to ensure high‐quality financial reporting. In addition, we find that this positive reaction is concentrated among firms with relatively strong corporate governance, consistent with accounting financial expertise complementing strong governance, possibly because strong governance helps channel the expertise toward enhancing shareholder value. Together, these findings are consistent with financial expertise on audit committees improving corporate governance but only when both the expert and the appointing firm possess characteristics that facilitate the effective use of the expertise.
Vestibulo‐Ocular Reflex Abnormalities in Patients With Migraine
Authors: Helm Melvin R.
Published: April 2005

Objective.—To investigate the high‐frequency vestibulo‐ocular reflex (VOR) in patients with migraine, with and without dizziness and aura.

Background.—Migraine is a common cause of dizziness. Although many vestibular testing abnormalities have been documented in migraine patients, high‐frequency VOR abnormalities have not been reported.

Methods.—Thirty‐nine consecutive patients with migraine were studied with the vestibular autorotation test (VAT®). The patients were subclassified as having migraine headache only, migraine with visual aura, migraine with dizziness, or migraine with visual aura and dizziness.

Results.—Only a high vertical phase in the 4 to 5 Hz range was correlated with migraine (correlation coefficients: .356, P= .03). Further analysis revealed that an abnormal 4 to 5 Hz vertical phase result also was positively correlated with migraine with aura and dizziness (correlation coefficients: .392).

Conclusion.—The results suggest that patients with migraine may have an abnormal vertical VOR at higher head movement frequencies. Migraine patients with visual aura and dizziness are even more likely to have this abnormality.
Pilot Study Evaluating Preference for 3‐mg Versus 6‐mg Subcutaneous Sumatriptan
Authors: Landy Stephen H. , McGinnis Judy E. , McDonald Susan A.
Published: April 2005

Background.—Subcutaneous sumatriptan (6 mg) is undeniably an excellent treatment of migraine. However, some patients have avoided using 6 mg sumatriptan because of unpleasant or unwanted side effects.

Objective.—To evaluate the efficacy of subcutaneous sumatriptan (3 mg) during a moderate or severe migraine attack.

Methods.—Thirty subcutaneous sumatriptan‐naïve patients with a history of migraine with and without aura treated their next two moderate or severe migraines with either 3‐mg or 6‐mg sumatriptan injection. The primary endpoint was whether patients preferred the low‐dose (3 mg) or the high‐dose (6 mg) subcutaneous sumatriptan. Other objectives included percentage of patients pain free at 15 and 30 minutes, 1 and 2 hours; a pain‐free response lasting between 2 and 24 hours, patient satisfaction, and acceptability of formulation. A new combination endpoint (efficacy and lack of significant side effects) was also evaluated.

Results.—Eighty percent of patients preferred 3‐mg over 6‐mg subcutaneous sumatriptan. At 1 hour postdose 57% of patients were pain free with 3 mg and 53% with 6 mg. At 2 hours postdose 87% were pain free with 3 mg and 80% with 6 mg. A sustained pain‐free response was obtained by 70 to 80% of patients. When combining a pain‐free response at 2 hours and a sustained pain‐free response at 24 hours with no significant side effects, more patients met the endpoint with 3 mg (63 to 67%) than with 6 mg (33 to 50%).

Conclusions.—Combining efficacy and tolerability endpoints may be clinically meaningful and reflective of real‐world expectations. In some patients, a lower dose of sumatriptan injection may be beneficial.
The Effects of Greater Occipital Nerve Block and Trigger Point Injection on Brush Allodynia and Pain in Migraine
Authors: Ashkenazi Avi , Young William B.
Published: April 2005

Objective.—To evaluate the effect of GONB, with or without trigger point injection (TPI), on dynamic mechanical (brush) allodynia (BA) and on head pain in migraine.

Background.—Patients with migraine often have cutaneous allodynia that is related to sensitization of central pain neurons. Greater occipital nerve block (GONB) is an effective treatment for migraine headache; however, its effect on cutaneous allodynia in migraine is unknown.

Methods.—We studied patients with migraine and BA who were treated with GONB with or without TPI. Demographic data, migraine history, and headache features were documented. Allodynia was evaluated using a structured questionnaire and by applying a 4 × 4‐inch gauze pad to skin areas in the trigeminal and cervical dermatomes. Degree of allodynia (the allodynia score) was measured on a 100‐mm visual analog scale (VAS) before treatment and 10 and 20 minutes thereafter. Headache levels were assessed using an 11‐point verbal scale. Allodynia scores, as well as headache levels, before and after treatment were compared.

Results.—Nineteen patients were studied. Mean age was 43.6 ± 11.8 years. Twenty minutes after treatment, headache was reduced in 17 patients (89.5%) and did not change in 2 (10.5%). The average headache level was 6.53 before treatment and 3.47, 20 minutes after it. The average allodynia score decreased after 20 minutes in all patients. Average allodynia score per site was reduced by 18.69 mm and 13.74 mm in the trigeminal and cervical areas, respectively. There was a positive correlation between allodynia index, obtained through the questionnaire, and allodynia score, obtained by examination.

Conclusion.—GONB, with or without TPI, reduced both head pain and brush allodynia in this migraine patient group.
Acetazolamide Efficacy and Tolerability in Migraine With Aura: A Pilot Study
Authors: De Simone Roberto , Marano Enrico , Di Stasio Emanuela , Bonuso Salvatore , Fiorillo Chiara , Bonavita Vincenzo
Published: April 2005

The study was an open uncontrolled pilot trial to test the efficacy and the tolerability of acetazolamide in a group of 22 outpatients suffering from migraine with aura (MA) with at least one aura episode in the last 2 months.
General Principles of Migraine Management: The Changing Role of Prevention
Authors: Loder Elizabeth , Biondi David
Published: April 2005

The role of preventive treatment in the management of migraine must be reassessed. Many patients who would benefit from preventive therapy do not receive it, and many might benefit from earlier and more aggressive use of preventive therapy. Physicians who treat migraine have long recognized that a subset of patients with episodic migraine evolve to chronic forms of the disorder that are difficult to treat and have a poor outcome. This article reviews the evidence for current and emerging prophylactic migraine treatment and raises the possibility that timely use of prophylactic treatment might modify or prevent the transformation to chronic migraine and the extreme disability that characterizes a small but significant subset of the migraine population. Along with aggressive treatment of the acute pain and other symptoms of migraine, prevention of progression to severe forms of this disorder will increasingly be a focus and goal of the treatment.
Migraine Pathophysiology
Authors: Goadsby Peter J
Published: April 2005

A combination of basic science and human physiology, particularly functional neuroimaging, has radically altered our understanding of migraine with a focus on brain mechanisms for this common and disabling disorder. Genetic studies have begun to provide plausible targets for the basic molecular defect in terms of ion channels, albeit thus far in the rare condition of familial hemiplegic migraine (FHM). Migraine pathophysiology involves the trigeminovascular system and central nervous system modulation of the pain‐producing structures of the cranium. The degree to which head pain results from the activation of the nociceptors of pain‐producing intracranial structures, or to the facilitation or lack of inhibition of afferent signals, is not clear at this time. An understanding of the pain mechanism is likely to provide insights into the mechanisms underlying the more generalized sensory dysfunction that is so typical of migraine.
Management of Chronic Daily Headache: Challenges in Clinical Practice
Authors: Saper Joel R. , Dodick David , Gladstone Jonathan P.
Published: April 2005

Chronic daily headache (CHD) refers to a category of headache disorders that are characterized by headaches occurring on more than 15 days per month. This category is subdivided into long‐ and short‐duration (>4 or <4 hours) CDH disorders based on the duration of individual headache attacks. Examples of long‐duration CDH include transformed migraine (TM), chronic migraine (CM), new daily persistent headache (NDPH), acute medication overuse headache, and hemicrania continua (HC). The goal of this review is to enable clinicians to accurately diagnose and effectively manage patients with long‐duration CDH. Patients with CDH often require an aggressive and comprehensive treatment approach that includes a combination of acute and preventive medications, as well as nondrug therapies.
Topiramate in Migraine Prevention
Authors: Silberstein Stephen D.
Published: April 2005

The efficacy of topiramate in migraine prevention (prophylaxis) was established in two multicenter, randomized, double‐blind, placebo‐controlled, pivotal trials. Topiramate has received regulatory approval for use in adults for migraine prophylaxis (prevention) in the US and numerous other countries, including France, Ireland, Switzerland, Brazil, Taiwan, Spain, and Australia. Treatment with 100 or 200 mg per day of topiramate was associated with significant reductions in the frequency of migraine headaches, number of migraine days, and use of acute medications. No increase in efficacy was observed between 100 and 200 mg per day of topiramate. Based on efficacy and tolerability, 100 mg per day of topiramate should be the initial target dose for most patients. The most common adverse events were paresthesia, fatigue, decreased appetite, nausea, diarrhea, weight decrease, and taste perversion. Topiramate is a first‐line migraine preventive drug and should especially be considered as a preferred treatment for all patients who are concerned about gaining weight, who are currently overweight, or who have coexisting epilepsy.
Brain Hyperexcitability: The Basis for Antiepileptic Drugs in Migraine Prevention
Authors: Welch K. Michael
Published: April 2005

Abnormal brain excitability may provide the susceptibility for triggering migraine attacks. Antiepileptic drugs may diminish neuronal excitability and consequently reduce the frequency of migraine. Because migraine aura is predominantly visual, hyperexcitability of the occipital cortex has been the focus of investigations. Functional magnetic resonance imaging of the brain and magnetoencephalography provide the most consistent evidence for the role of brain hyperexcitability in migraine and confirm that triggering an abnormal electric and metabolic event consistent with the cortical spreading depression (CSD) of Leao is anatomically and functionally linked with migraine aura symptoms. Future drug discovery should focus on the interface between the excitable cell and the earliest events of CSD.
Co–Teaching in Middle School Classrooms under Routine Conditions: Does the Instructional Experience Differ for Students with Disabilities in Co–Taught and Solo–Taught Classes?
Authors: Magiera Kathleen , Zigmond Naomi
Published: April 2005

Co–teaching is a popular strategy for implementing the inclusion of students with disabilities within secondary general education classrooms. However, we have little data regarding its effectiveness under routine conditions of educational practice. This study examined whether there was an “additive effect” of the special education teacher on the instructional experiences of students with disabilities as compared with the experiences of the same students taught by only the general education teacher under routine conditions. Observers used time sampling methods to document how students with disabilities spent their time in 11 middle school co–taught classes. Statistically significant differences were found for targeted students in terms of general education teacher interaction and individual instruction. General education teachers spent significantly less time with students with disabilities when the special education teacher was present. In addition, students with disabilities received significantly more individual instruction when the special education teacher was present. However, these differences were of limited practical significance.
Subgroups of Attributional Profiles in Students with Learning Difficulties and Their Relation to Self–Concept and Academic Goals
Authors: Núñez José Carlos , González–Pienda Julio A. , González–Pumariega Soledad , Roces Cristina , Alvarez Luis , González Paloma , Cabanach Ramón G. , Valle Antonio , Rodríguez Susana
Published: April 2005

The aim of this article was fourfold: first, to determine whether there are significant differences between students with ( N= 173) and without learning disabilities (LD; N= 172) in the dimensions of self–concept, causal attributions, and academic goals. Second, to determine whether students with LD present a uniform attributional profile or whether there are subgroups of attributional profiles among students with LD. Third, to explore differences between these profiles on the dimensions of self–concept, academic goals, perception of competence–incompetence, persistence when faced with failure, peer relationships, and academic achievement. Fourth, to determine whether there are significant differences in the dimensions of self–concept and academic goals between NLD students and the different LD subgroups. The results indicate the existence of two very distinct attributional profiles in students with LD (Helplessness Profile and Adaptive Profile). The implications of these data with regard to theory and research, as well as educational practice, are discussed.
A Drop in the Bucket: Randomized Controlled Trials Testing Reading and Math Interventions
Authors: Seethaler Pamela M. , Fuchs Lynn S.
Published: April 2005

The purpose of this study was to determine the proportion of empirical studies published in the last 5 years in a sample of special education peer–reviewed journals that (1) assessed the effects of reading and math interventions with group designs and (2) used random assignment to treatment conditions to test those interventions. A hand search of articles from the Journal of Special Education, Exceptional Children, Learning Disabilities Research & Practice, the Journal of Learning Disabilities, and School Psychology Review yielded 806 relevant articles, of which 5.46 percent tested a reading or math intervention using a group design and 4.22 percent used random assignment. These findings indicate that randomized experimental designs, which offer the highest level of evidence of an intervention's efficacy, are underrepresented in the literature, at least in the area of reading and math interventions.
Individualized Course–Specific Strategy Instruction for College Students with Learning Disabilities and ADHD: Lessons Learned from a Model Demonstration Project
Authors: Allsopp David H. , Minskoff Esther H. , Bolt Les
Published: April 2005

This 3–year Model Demonstration Project involved the development and field testing of an individualized course–specific strategy instruction model with college students with learning disabilities and Attention Deficit Hyperactivity Disorder (ADHD). The 46 participants received individualized semester–long strategy instruction by graduate students in special education. A variety of data sources were used to evaluate the implementation of the model as well as the academic success of students who received individualized strategy instruction. Quantitative analyses indicated that the group as a whole as well as the subset of students on probation and suspension significantly improved their grades and sustained this improvement over time. Qualitative analysis identified two factors related to improvement: independent use of strategies and the supportive nature of the strategy instructor–student relationship. Qualitative analysis also identified two factors related to nonimprovement: academic/cognitive skill deficits and emotional/medication–related issues. Implications of the model for postsecondary education and suggestions for future research are discussed.
Writing in Mathematics: An Alternative Form of Communication for Academically Low–Achieving Students
Authors: Baxter Juliet A. , Woodward John , Olson Deborah
Published: April 2005

Classroom communication figures prominently in current math reform efforts. In this study, we analyze how one teacher used writing to support communication in a seventh–grade, low–track mathematics class. For one school year, we studied four low–achieving students in the class. Students wrote in journals on a weekly basis. Using classroom observations and interviews with the teacher, we developed profiles of the four students, capturing their participation in class discussions. The profiles highlighted an important similarity among the four students: marginal participation in both small–group and whole–class discussions. However, our analysis of the students’ journals identified multiple instances where the students were able to explain their mathematical reasoning, revealing their conceptual understanding, ability to explain, and skill at representing a problem. In this respect, journals potentially facilitate another important form of classroom communication. The promise of writing is that it offers an alternative to the visions of classroom communication that are strictly oral in nature.
Highway Security and Terrorism
Authors: Field Mary A.
Published: April 2005

This article presents an overview of highway transportation security before and after the terrorist attacks on September 11, 2001, in the context of hazardous materials (hazmat) transportation. It is primarily focused on the Federal Motor Carrier Safety Administration (FMCSA) regulation of motor carrier transportation of hazmat and post‐9/11 efforts to prevent acquisition by terrorists of certain classes of hazmat. In the context of homeland security, motor carrier transportation of hazmat is receiving heightened attention. It should be cautioned, the article highlights a limited number of activities at the federal level only to provide the reader with a sense of ongoing government and industry activities to improve transportation security.
Seeing around Corners: Crafting the New Department of Homeland Security1
Authors: Haynes Wendy
Published: April 2005

The development of the nation's homeland security agenda, including building the behemoth new Department of Homeland Security, will for decades to come provide a rich laboratory for scholars, public managers, consultants, and other observers and analysts. In this article, we begin to describe some of the history, key players and institutions, major policy instruments, and organizational challenges in the rapidly evolving arena of homeland security. This article carries with it two primary purposes: (1) to identify some of the key documents and federal‐level initiatives since September 11, and (2) to suggest several areas that beg for additional attention from those who care about effective public policy and administration, whether the particular bent be toward scholarship or practice.
Fighting Poverty with Mobility: A Normative Policy Analysis1
Authors: Imbroscio David L.
Published: April 2005

Concentrated urban poverty is America's deepest social problem. Eliminating it stands as our nation's greatest challenge. In this article I analyze from a normative perspective antipoverty policies that attempt to address this problem via “mobility,” that is, policies that attempt to disperse the urban poor to suburban locations. I find these policies to be normatively problematic on two grounds: the level coercion experienced by (and the corresponding lack of free choice given) a vulnerable population and the undesirable effects (in the current context of American urban development) caused by failing to regard established neighborhoods as stable communities. The results of this analysis indicate strongly the need to generate increased levels of economic activity in America's inner cities, and I suggest that more research on this issue be conducted with an eye toward formulating and implementing a comprehensive strategy to bring about inner‐city revitalization.
Viscosity and Acoustic Behavior of Ceramic Suspensions Optimized for Phase‐Change Ink‐Jet Printing
Authors: Reis Nuno , Ainsley Christopher , Derby Brian
Published: April 2005

The application of ink‐jet printing technologies to direct‐write and freeform fabrication of ceramics requires the development of appropriate printing fluids. The critical parameter controlling fluid printing ability is viscosity, although surface tension and density are also important. Additionally, in piezoelectric‐driven ink‐jets, drop ejection is governed by a series of electric pulses exciting a transducer at acoustic frequencies and hence the fluid acoustic wave speed is also important. Here, suspensions of sterically stabilized fine ceramic powders in solidifying hydrocarbon systems exhibiting suitable rheology for ink‐jet printing have been formulated and their acoustic behavior has been characterized. For the particle sizes and frequencies used in this study, acoustic wave speed as a function of solids content is accurately predicted by effective medium theory. Suspensions containing up to 45% particulate by volume can be successfully passed through conventional printing heads.
Effects of Bias Electric Fields on the Non‐linear Ferroelastic Behavior of Soft Lead Zirconate Titanate Piezoceramics
Authors: Zhou Dayu , Kamlah Marc , Munz Dietrich
Published: April 2005

Modern piezoelectric transducers normally have complicated structures and work under severe loading conditions. Due to their inherent domain‐switching processes, the real response of piezoceramics under large‐signal loading is dominated by a significantly non‐linear behavior that is to be considered in reliability assessment and devices design. This paper presents systematic measurements of the non‐linear depolarization and strain behavior of soft lead zirconate titanate piezoceramics over a wide range of compression loads and bias electric fields. An attempt has been made to explain the experimental findings by simultaneously taking into account the contributions of dielectric response, elastic deformation, irreversible domain switching, and piezoeffects.
Evaporation‐Assisted Formation of Three‐Dimensional Photonic Crystals
Authors: Hsiao Sheng‐Yuan , Wong David Shan Hill , Lu Shih‐Yuan
Published: April 2005

The process of evaporation‐assisted formation of three‐dimensional photonic crystals was studied. The photonic crystals were fabricated by stacking uniform‐sized silica spheres into regularly arranged structure with solvent evaporation and sedimentation. Effects of important process parameters, including type of solvent (water and ethanol), system temperature (40° and 60°C), and material for sedimentation cell (quartz, polymethyl methacrylate, and Teflon), on structure regularity of the resulting photonic crystal were investigated. The structure regularity was evaluated with scanning electron microscope graphs and stop band depth achieved in optical absorption spectra. As revealed from the experimental results, photonic crystals of better quality were obtained by using suspending solvents of higher surface tension (water), lower system temperatures (40°C), and sedimentation cell materials of higher critical surface tension of wetting (quartz).
Modification of Al Particle Surfaces by γ‐Al2O3 and Its Effect on the Corrosion Behavior of Al
Authors: Deng Zhen‐Yan , Liu Yu‐Fu , Tanaka Yoshihisa , Ye Jinhua , Sakka Yoshio
Published: April 2005

Metal Al particle surfaces were modified by fine γ‐Al2O3 grains using a mixture of Al and Al(OH)3 powders, which was pressureless sintered at a temperature of 600°C in vacuum. All the constituents on original Al particle surfaces were transformed into γ‐Al2O3 phase after sintering. No dense passive oxide layers on Al particle surfaces were formed even after the modified Al particles were exposed to oxidation environment. The modified Al particles could continuously react with pure water and generate hydrogen at room temperature. The present finding implies that metal Al could become hydrogen‐generation material by surface modification.
Multi‐Walled Carbon Nanotube Coatings Using Electrophoretic Deposition (EPD)
Authors: Thomas B. J. C. , Boccaccini A. R. , Shaffer M. S. P.
Published: April 2005

A method based on electrophoretic deposition (EPD) has been developed to produce uniform deposits of multi‐walled carbon nanotubes on stainless‐steel substrates. Aqueous suspensions were used under constant voltage conditions in the range of 5–50 V, with deposition times ranging from 0.5 to 10 min. The thickness of the coatings was controlled by variation of voltage and deposition time during EPD. Coatings of up to 10 μm thickness were achieved, with a homogeneous microstructure. The EPD technique is fast, effective, and can be applied to complex shapes. Possible applications are in heat extraction devices or porous coatings for tissue engineering scaffolds.
Mesoporous Calcium Phosphate Via Post‐Treatment of α‐TCP
Authors: Kitamura Makoto , Ohtsuki Chikara , Ogata Shin‐ichi , Kamitakahara Masanobu , Tanihara Masao , Miyazaki Toshiki
Published: April 2005

α‐Tricalcium phosphate (α‐TCP) macroporous ceramic scaffold was chemically treated with a buffered solution at pH=4. Mesopores were formed in the scaffold after the treatment to result in a remarkable increase in surface area of the scaffold. The increase in the surface area is caused by precipitation of octacalcium phosphate (OCP). Bimodal pore size distribution consisting of mesopores and macropores obtained by the treatment of α‐TCP scaffold having higher initial porosity brought about high adsorption of bovine serum albumin (BSA) than monomodal pore size distribution of mesopores. Adsorption of BSA, acidic protein, was suggested to result from crystallographic characters of OCP.
Crystalline Phases and YAG Laser‐Induced Crystallization in Sm2O3–Bi2O3–B2O3 Glasses
Authors: Honma Tsuyoshi , Benino Yasuhiko , Fujiwara Takumi , Komatsu Takayuki , Sato Ryuji
Published: April 2005

The glass formation region, crystalline phases, second harmonic (SH) generation, and Nd:yttrium aluminum garnet (YAG) laser‐induced crystallization in the Sm2O3–Bi2O3–B2O3 system were clarified. The crystalline phases of Bi4B2O9, Bi3B5O12, BiBO3, SmxBi1−xBO3, and SmB3O6 were formed through the usual crystallization in an electric furnace. The crystallized glasses consisting of BiBO3 and SmxBi1−xBO3 showed SH generations. The formation of the nonlinear optical BiB3O6 phase was not confirmed. The formation (writing) region of crystal lines consisting of SmxBi1−xBO3 by YAG laser irradiation was determined, in which Sm2O3 contents were∼10 mol%. The present study demonstrates that Sm2O3–Bi2O3–B2O3 glasses are promising materials for optical functional applications.
Surface Orientation and Wetting Phenomena in Si/α‐Alumina System at 1723 K
Authors: Shen Ping , Fujii Hidetoshi , Matsumoto Taihei , Nogi Kiyoshi
Published: April 2005

Wetting phenomena and the effect of alumina surface orientation on the wettability in Si/α‐Al2O3 system were studied by an improved sessile drop method using
, , C(0001) faces of single crystals and polycrystals at 1723 K in a reducing Ar–3% H2 atmosphere. The contact angles show a vibration behavior for all the single crystals but to a less extent for the polycrystals. The extent of the vibration correlates not only with the reaction intensity but also with the stability of the Si droplet on the alumina surfaces. The interfacial reaction leads to the formation of a series of reaction rings, which is more serious at the single crystal surfaces. More importantly, the wettability is dependent on the alumina surface orientation, with the intrinsic contact angles being about 98±2°, 101±1°, 69±1°, and 98±2°, respectively, for the, , C(0001) and polycrystal α‐Al2O3 substrates. The much smaller contact angle for molten Si on the C(0001) surface is explained by the favorable reduction in the Si/α‐Al2O3 interfacial free energy by the terminated and enriched aluminum atoms at the reconstructedsurface. The importance of the aluminum presence at the Si/α‐Al2O3 interface to the wettability of this system was further demonstrated by a substantial improvement in the wettability of theα‐Al2O3substrates by Si–Al alloys.
Influence of Sucrose Addition on Rheology of Alumina Slurries Dispersed with a Polyacrylate Dispersant
Authors: Pradhan Mamata , Bhargava Parag
Published: April 2005

The effect of sucrose addition on rheology of alumina slurries, dispersed with a polyacrylate dispersant (Darvan 821 A), was studied for different alumina loading. Smaller amount of sucrose addition (10 wt%) had a more significant influence on rheological behavior of the slurries than the incremental addition to 30 wt% sucrose. Addition of sucrose resulted in a decrease in the apparent yield stress, viscosity, thixotropy, and increase in non‐Newtonian index as compared with the slurries containing just the polyacrylate, indicating weakening of the inter‐particle network. Weakening of the inter‐particle network arose from the enhanced steric hindrance because of the presence of sucrose molecules in association with the polyacrylate molecules adsorbed on alumina particle surfaces. This association is because of intermolecular hydrogen bond formation between free hydroxyl (−OH) groups of sucrose and carboxylate ions of polyacrylate molecules. Use of sucrose resulted in cast green bodies with higher strength.
Particle Formation During Spray Pyrolysis of Lead Zirconate Titanate
Authors: Nimmo William , Ali Naseef J. , Brydson Rik , Calvert Clair , Milne Steven J.
Published: April 2005

A twin‐fluid atomization spray pyrolysis technique has been used to produce lead zirconate titanate (PZT) powders from a sol–gel precursor solution. Samples were removed from ports sited along the reactor in order to examine particle development at progressive stages of pyrolysis. The total time in the reactor was 2.6 s. The size and shape of the particles showed no change between the first port (190°C) and the hottest part of the reactor (820°C), indicating that the physical structure of the particles was established during the initial drying stages. The powders were mainly composed of spherical particles, but irregular forms were also present, which were thought to result from the inward collapse of hollow gelatinous particles. Crystallization of PZT commenced at around 700°C, initially to a pyrochlore or fluorite intermediate phase, with the desired perovskite phase developing between 790°C and 815°C. However, a minor amount of the pyrochlore/fluorite phase persisted in the final powder. The final powders also contained basic lead carbonate, 2PbCO3·Pb(OH)2, which existed in the form of elongated crystallites on the surface of the PZT particles.
Fractography, Mechanical Properties, and Microstructure of Commercial Silicon Nitride–Titanium Nitride Composites
Authors: Blugan Gurdial , Hadad Mousab , Janczak‐Rusch Jolanta , Kuebler Jakob , Graule Thomas
Published: April 2005

Commercial‐grade Si3N4–TiN composites with 0, 10, 20, and 30 wt% TiN content have been characterized. Submicrometer grain‐size Si3N4 was reinforced with fine TiN grains. Density, Young's modulus, coefficient of thermal expansion, and fracture toughness increased linearly with TiN content. Increased strength was observed in the Si3N4+20 wt% TiN, and Si3N4+30 wt% TiN composites. Fractography was used to characterize the different types of fracture origins. Improvements in toughness and strength are due to residual stresses in the Si3N4 matrix and the TiN particles. A threefold improvement in dry wear resistance of the Si3N4+30 wt% TiN composite over the Si3N4 matrix was observed.
New Strategies for Preparing NanoSized Silicon Nitride Ceramics
Authors: Xu Xin , Nishimura Toshiyuki , Hirosaki Naoto , Xie Rong‐Jun , Zhu Yinchun , Yamamoto Yoshinobu , Tanaka Hidehiko
Published: April 2005

We report the preparation of nanosized silicon nitride (Si3N4) ceramics via high‐energy mechanical milling and subsequent spark plasma sintering. A starting powder mixture consisting of ultrafine β‐Si3N4 and sintering additives of 5‐mol% Y2O3 and 2‐mol% Al2O3 was prepared by high‐energy mechanical milling. After milling, the powder mixture was mostly transformed into a non‐equilibrium amorphous phase containing a large quantity of well‐dispersed nanocrystalline β‐Si3N4 particles. This powder precursor was then consolidated by spark plasma sintering at a temperature as low as 1600°C for 5 min at a heating rate of 300°C/min. The fully densified sample consisted of homogeneous nano‐Si3N4 grains with an average diameter of about 70 nm, which led to noticeable high‐temperature ductility and elevated hardness.
Ceramic–Ceramic Actuator Composed of Two Piezoelectric Layers with Opposite Poling Directions
Authors: Yoon Chang‐Bun , Lee Seung Ho , Park Gun‐Tae , Kim Hyoun‐Ee
Published: April 2005

A ceramic–ceramic actuator composed of two piezoelectric ceramic layers with opposite poling directions was developed. One layer of the actuator had a high coercive electric field (PZT (Pb(Zr,Ti)O3)‐I; Ec=1.1 kV/mm), while the other had a relatively low coercive electric field (PZT‐II; Ec=0.6 kV/mm). The actuator was fabricated by cofiring a green compact composed of the PZT‐I powder on top of the PZT‐II powder. When an electric field >1.1 kV/mm was applied to the sintered body, the whole specimen was poled in one direction. Subsequently, by applying a field between 0.6 and 1.1 kV/mm, only the PZT‐II layer was switched to the other direction. When an electric field was applied to this oppositely poled two‐layer specimen, one layer of the specimen expanded while the other layer shrank. As a result of these reverse dilations, the actuator was bent into a dome shape, yielding a large axial displacement at the center. The displacement of this actuator with dimensions of 20 mm (diameter) × 1 mm (thickness) was 16 μm at 0.9 kV/mm.
Effect of AC‐Powered Water Electrolysis on the Structural and Optical Properties of Indium Tin Oxide Thin Films
Authors: Wang Yu , Chen Wan Ping , Cheng K. C. , Chan Helen Lai Wah , Choy Chung Loong
Published: April 2005

The changes in the structure and optical properties of indium tin oxide (ITO) thin films that were subjected to water electrolysis using an alternating current power source were investigated. X‐ray diffraction indicated that the film was reduced to metallic indium after the treatment. Scanning electron microscopy revealed that the film became porous after the treatment. These structural changes had led to a dramatic degradation in the optical properties of ITO. The electrochemical mechanism responsible for the changes was discussed.
Microstructure and Dielectric Properties of Textured SrTiO3 Thin Films
Authors: Schmidt Steffen , Lu Jiwei , Keane Sean P. , Bregante Lia D. , Klenov Dmitri O. , Stemmer Susanne
Published: April 2005

We investigate the relationship between microstructure and dielectric properties of textured SrTiO3 thin films deposited by radio‐frequency magnetron sputtering on epitaxial Pt electrodes on sapphire substrates. The microstructures of Pt electrodes and SrTiO3 films are studied by transmission electron microscopy, atomic force microscopy, and X‐ray diffraction. SrTiO3 films grown on as‐deposited and annealed Pt electrodes, respectively, consist of a mixture of (111)‐ and (110)‐oriented grains. Temperature‐dependent dielectric measurements show that differences in texture and microstructure are reflected in the Curie–Weiss behavior of the SrTiO3 films. Phenomenological models that account for the effects of thermal mismatch strain on the dielectric behavior are developed for different film textures. The models predict that at a given temperature, paraelectric (111)‐oriented films of SrTiO3 on tensile substrates will have a higher Curie–Weiss temperature and a greater dielectric constant than (110)‐oriented films or bulk SrTiO3. The experimental dielectric behavior is compared with the predictions from theory, and different contributions, such as interfacial layers, film stress, and microstructure, to the Curie–Weiss behavior are discussed.
Synthesis and Properties of CdSe‐Sensitized Rutile TiO2 Nanocrystals as a Visible Light‐Responsive Photocatalyst
Authors: Liu Hongyan , Gao Lian
Published: April 2005

CdSe‐modified rutile TiO2 nanocrystals with mercaptoacetic acid as a stabilizer were prepared by the hydrothermal method. The photoactivities of the new photocatalyst under visible light illumination were demonstrated by the degradation of methylene blue (MB). The effects of CdSe content on the absorption spectra and photoactivities were discussed. After sensitization, TiO2 significantly responded to visible light illumination and the visible light photoactivities also increased.