bluuebunny/crossref_metadata_2025 huggingface dataset:
Mast Cell Involvement in the Pathophysiology of Migraine Headache: A Hypothesis
Authors: Levy Dan , Burstein Rami , Strassman Andrew M.
Published: May 2006

Migraine attacks are triggered by a variety of conditions including endogenous and exogenous factors. Evidence suggests that activation and sensitization of primary afferent meningeal nociceptive neurons, the peripheral arm of the trigeminovascular system, constitutes one of the earliest events promoting the intracranial pain of migraine. However, the link between the varied triggering factors and activation of meningeal nociceptive neurons is not completely understood. Local inflammation with release of mediators from local immune/inflammatory cells is thought to play a critical role in such neuronal response. Meningeal mast cells may play such a role by virtue of their proximity both to meningeal blood vessels and nociceptive axons and their ability to release a host of proinflammatory/algesic mediators. This paper reviews data relevant to the hypothesis that mast cells, upon activation by migraine triggers, contribute to the genesis of migraine headache. Epidemiologic findings, clinical data, and observations on anatomical and physiological characteristics of mast cells converge to suggest an important role of these immune cells in the pathogenesis of migraine. Migraine triggers might directly or indirectly promote mediator secretion from meningeal mast cells, and thereby cause inflammation and activation of the trigeminovascular system. While consistent, the evidence supporting mast cell involvement in the genesis of migraine is largely circumstantial to date. Further studies are needed to test directly the nature of mast cell involvement in the pathogenesis of migraine headache.
Genetics of Migraine: An Update
Authors: Gardner Kathy L.
Published: May 2006

Observations including the long‐recognized tendency of migraine to run in families, the high concordance rates for migraine in twins reared together or apart, and the association of specific mutations with a rare migraine form are consistent with a genetic contribution to the disorder. This paper summarizes major findings to date on the genetics of migraine. Study of the heritability of migraine, particularly the common forms of migraine, is beset by several challenges including the absence of easily measurable biological markers, uncertainty about the etiologic and clinical overlap among migraine types, and the apparently complex interplay of environmental and genetic factors in determining migraine phenotype. Nevertheless, significant progress has been realized in recent years. Familial hemiplegic migraine, a rare migraine variant, appears to be transmitted by a Mendelian, autosomal dominant mode of inheritance involving mutations in at least 2 genes. These genes do not seem to be critically involved in the other forms of migraine; however, several other susceptibility loci for more common forms of migraine have been identified in recent genome‐wide screens and candidate‐locus studies. These and other data suggest that the genetic contribution to migraine is complex, multifactorial, and subject to significant modification by environmental factors.
Invertebrate Modeling of a Migraine Channelopathy
Authors: Estevez Miguel
Published: May 2006

Migraine is a chronic episodic disorder that has been linked to abnormalities in serotonin signaling and abnormal function of a presynaptic voltage‐gated calcium channel, CACNA1A. Although the importance of serotonin to migraine tendency suggests a link between serotonergic signaling and CACNA1A function, the nature of this connection remains unclear in vertebrate studies. This article reviews findings, based on an invertebrate model of CACNA1A dysfunction, which suggest a potential connection between serotonergic and calcium channel abnormalities in migraine. Neurons of the invertebrate species Caenorhabditis elegans express a voltage‐gated calcium channel, UNC‐2, which is the closest ortholog in C. elegans of human CACNA1A. Mutations in unc‐2, the gene that encodes this invertebrate channel, cause the animals to be lethargic and uncoordinated. By identifying the genes that could be altered in such a way as to suppress the lethargic phenotype of unc‐2, a signaling pathway has been identified through which UNC‐2 calcium channel function antagonizes a transforming growth factor‐β (TGF‐β) pathway modulating locomotion. In C. elegans, serotonergic signaling can inhibit the rate of movement. The UNC‐2/transforming growth factor‐β pathway identified regulates the expression of a gene encoding the rate‐limiting enzyme for serotonin synthesis, tryptophan hydroxylase. The evolutionary and functional relationship between the UNC‐2 channel and the migraine‐associated CACNA1A channel was further confirmed through experiments showing that transgenic expression of human CACNA1A can suppress the lethargic and serotonin‐deficient phenotypes of unc‐2 mutant animals. The findings in this invertebrate model constitute the first direct demonstration of how CACNA1A function might affect the levels of serotonin, a neurotransmitter known to be important in migraine.
Functional Imaging of the Trigeminal System: Applications to Migraine Pathophysiology
Authors: Borsook David , Burstein Rami , Moulton Eric , Becerra Lino
Published: May 2006

Background.—Based largely on data from animal models, migraine is hypothesized to involve changes in neural function in brain areas that mediate nociception—specifically, the trigeminal nerve, spinal trigeminal nucleus, and thalamus. These hypotheses about migraine pathophysiology can be tested directly in humans for the first time, with recent advances in functional neuroimaging techniques, which allow assessment of functional activity of specific brain areas. This article discusses the hypothesized role of the trigeminovascular pain system in migraine, reviews recent findings involving functional imaging of the human trigeminal system, and considers applications of functional imaging in the study of migraine pathophysiology. Functional neuroimaging is the only noninvasive approach for the objective measurement of changes in neural activity in humans. Functional magnetic resonance imaging has been applied to the measurement of neural activation of the trigeminal nociceptive system in healthy volunteers, and in patients with pain syndromes such as trigeminal pain. Conclusions.—The demonstrated utility of functional magnetic resonance imaging at elucidating, in a regionally specific manner, the functional and temporal changes in neural activity in the trigeminal nociceptive system, promises to make it a useful tool for the study of migraine pathophysiology and the evaluation of therapeutic interventions.
Neurochemistry of Trigeminal Activation in an Animal Model of Migraine
Authors: Oshinsky Michael L. , Luo Jia
Published: May 2006

Research techniques such as electrophysiology, cFos protein expression, and other measurements of neuronal activation provide insights into the pathophysiology of pain processing in migraine, but they do not indicate the specific neurotransmitter systems involved. This paper summarizes data from microdialysis experiments in which changes in the neurochemistry of the trigeminal nucleus caudalis (TNC) were monitored during dural stimulation. Microdialysis allows the measurement of extracellular concentrations of neurotransmitters in a small area of the brain, in vivo, by means of a probe equipped with a semipermeable membrane. Microdialysis enables direct measurement of changes in extracellular concentrations of neurotransmitters in the intact animal over time in response to dural inflammation. Following the activation of the dural nociceptors, changes in the extracellular amino acid neurotransmitters in the deep lamina of the TNC were tracked. A 5‐minute application of inflammatory soup when compared with saline to the dura of rats induced a transient decrease in extracellular glutamate in the TNC at approximately 30 minutes postapplication. This short‐lived decrease was followed by a continuous increase in extracellular glutamate to a level of approximately 3 times the baseline value at 3 hours after application of the inflammatory soup. The time course of this increase in extracellular glutamate correlated with changes in sensory thresholds on the face of the rat from electrophysiological recordings of secondary sensory neurons in the TNC. No significant differences between the inflammatory soup and saline conditions were observed for extracellular concentrations of aspartate (an excitatory amino acid) or the inhibitory neurotransmitters gamma‐aminobutyric acid or glutamine. Results of these experiments support an integral role for glutamate in central sensitization of neurons in the TNC, and suggest an important contribution of glutamate to allodynia and hyperalgia in this animal model of migraine.
Release of potential immunomodulatory factors during platelet storage
Authors: Cognasse Fabrice , Boussoulade Françoise , Chavarin Patricia , Acquart Sophie , Fabrigli Patrick , Lamy Bernard , Garraud Olivier
Published: May 2006

BACKGROUND:  Blood platelets (PLTs) link the processes of hemostasis and inflammation. Recent studies have demonstrated that PLTs promote immunity and inflammation mainly by means of the CD40/CD40L pathway. Our objective was to describe the accumulation of cytokines in PLT concentrates during storage.

STUDY DESIGN AND METHODS:  Pools of PLT concentrates were prepared, separated from plasma, and resuspended in clinical‐grade storage medium; samples were taken on Days 0, 1, 2, 3, and 5 for analysis, without replacement (i.e., without soluble protein dilution). Interleukin (IL)‐6, IL‐8, PLT‐derived growth factor (PDGF)‐AA, soluble CD40 ligand (sCD40L), RANTES, and transforming growth factor‐β production were measured by specific enzyme‐linked immunosorbent assays.

RESULTS:  Over time, the levels of RANTES, IL‐8, and IL‐6 were stable. In contrast, the levels of PDGF‐AA and sCD40L increased. Ex vivo production of sCD40L was quantified at levels sufficient to induce B‐cell effects based on previous studies of in vitro induced B‐cell activation and differentiation by sCD40L. Cytokine and/or chemokine levels were generally higher in PLT concentrate supernatants and/or PLT lysates in comparison to PLT‐free plasma, allowing the determination of which cytokine and/or chemokine was absorbed or secreted by transfusion‐grade PLTs over time.

CONCLUSION:  Our data provide evidence that stored PLTs contain molecules with known immunomodulatory competence and secrete them differentially over time during storage for transfusion purposes.
Assessment of cord blood unit characteristics on the day of transplant: comparison with data issued by cord blood banks
Authors: Wagner Eric , Duval Michel , Dalle Jean‐Hugues , Morin Hugo , Bizier Sonia , Champagne Josette , Champagne Martin A.
Published: May 2006

BACKGROUND:  Selection of a cord blood (CB) unit for allogeneic transplantation relies on graft characterization results provided by cord blood banks (CBBs). The goal was to compare the graft characterization results obtained upon thawing and washing to those provided by CBBs at selection.

STUDY DESIGN AND METHODS:  With tests that assess CB graft characteristics known to impact engraftment, CB units have been analyzed after thaw and before infusion. Our results were compared to data provided by CBBs to determine the impact on engraftment and assess how CBB‐supplied information can affect future CB unit selection.

RESULTS:  Variability was noted as to the type of information provided by the different CBBs. Also, variability was found between the information provided by CBBs and the graft characterization results obtained upon thawing and washing. In some cases, CB measures known to be predictive of engraftment were found much lower than reported by CBBs. Only the total nucleated cell count, which is the main CB graft selection criterion besides HLA matching, correlated favorably.

CONCLUSIONS:  Our data reveal a high degree of variability in graft characteristics provided by CBBs and often poor correlation with results obtained on thawed and washed CB units. We suggest that standardized laboratory procedures aimed at graft characterization should be used by both CBBs and transplant centers to avoid unacceptable discrepancies.
Enhancing effect of platelet‐derived microvesicles on the invasive potential of breast cancer cells
Authors: Janowska‐Wieczorek Anna , Marquez‐Curtis Leah A. , Wysoczynski Marcin , Ratajczak Mariusz Z.
Published: May 2006

BACKGROUND:  Platelets (PLTs) have been postulated to play a role in cancer progression and metastasis. Recently, it was demonstrated that PLT‐derived microvesicles (PMVs) transfer various surface receptors and/or adhesion molecules to target cells and modulate their biological responses. In this work, it was hypothesized that PMVs interact with breast cancer cells, increasing their invasiveness.

STUDY DESIGN AND METHODS:  PMVs (isolated from outdated PLT concentrates) were incubated with three human breast cancer cell lines (MDA‐MB‐231, BT‐549, and T47D), and their effects on in vitro invasiveness of these cells (adhesion, expression of matrix metalloproteinases [MMPs], and chemoinvasion), as well as their interactions with stroma, were evaluated.

RESULTS:  We found that PMVs 1) transferred PLT‐derived integrin CD41 to the surface of breast cancer cells and enhanced their adhesion to endothelial cells; 2) increased CXCR4 expression and chemotaxis toward a stromal‐derived factor‐1 gradient in invasive MDA‐231 and BT‐549 cells; 3) increased phosphorylation of the mitogen‐activated protein kinase p42/44 and AKT signaling pathways; 4) stimulated the production of MMPs in invasive MDA‐231 and BT‐549 cells and their chemoinvasion across the reconstituted basement membrane Matrigel; and 5) induced the secretion of MMP‐9 by marrow fibroblasts and stimulated the secretion of both MMP‐2 and MMP‐9 in cocultures of fibroblasts with MDA‐MB‐231 cells.

CONCLUSION:  It was shown than PMVs enhance the in vitro invasive potential of invasive breast cancer cell lines and therefore could mediate the progression of breast cancer. These findings warrant further evaluation of the implications of PLT transfusions in cancer patients.
Tetanus toxoid provides efficient T‐cell help for the induction of HA‐1H cytotoxic T cells
Authors: Eiz‐Vesper Britta , Horn Peter A. , Daubert Claudia , Khattab Barbara , Blasczyk Rainer
Published: May 2006

BACKGROUND:  In vitro generation and expansion of leukemia‐reactive T cells may improve the efficacy and specificity of cellular immunotherapy against hematologic malignancies in the context of allogeneic stem cell transplantation. Since the expression of minor histocompatibility antigen HA‐1H is limited to hematopoietic cells, ex vivo generated HA‐1H‐specific CD8+ cytotoxic T lymphocytes (CTLs) can be used for adoptive immunotherapy.

STUDY DESIGN AND METHODS:  Numerous studies have shown that primary CTL induction from naïve precursors requires professional antigen‐presenting cells. Here, the feasibility of ex vivo induction of HA‐1H‐specific CD8+ CTLs is demonstrated from unfractionated peripheral blood mononuclear cells (PBMNCs) from healthy blood donors when CD4+ T‐cell help is provided during primary stimulation. As a stimulus for the induction of T‐cell help, tetanus toxoid (TT) was used.

RESULTS:  After the second restimulation cycle, approximately 1 percent of CD8+ T cells stained positively with the HLA‐A*0201/HA‐1H pentamer. Positive T cells were further expanded more than 1000‐fold by antigen‐independent stimulation with anti‐CD3/CD28 monoclonal antibodies. HA‐1H‐induced T cells showed the classical phenotype for CD8+ memory effector cells: the phenotype changed from a mixed CD45RA/RO phenotype to an activated phenotype characterized by high expression of CD45RO and no expression of CCR7. The generated T cells revealed a very potent CTL response, even at low E:T ratios.

CONCLUSION:  This study demonstrates that TT provides a very potent and cost‐effective tool for the in vitro induction of antigen‐specific CTLs from precursor PBMNCs that can easily be adapted to GMP conditions for translational purposes.
Disseminated histoplasmosis presenting as thrombotic microangiopathy
Authors: Dwyre Denis M. , Bell Adam M. , Siechen Kathleen , Sethi Sanjeev , Raife Thomas J.
Published: May 2006

BACKGROUND: Thrombotic microangiopathies (TMA) are systemic vasoocclusive disorders associated with significant morbidity and mortality. Rapid and reliable diagnosis of TMA is critical. The diagnosis is complicated by a lack of objective and sensitive laboratory testing as well as multiple concurrent diseases, including infectious processes.

CASE STUDY: We report two cases of disseminated histoplasmosis associated with TMA manifestations in renal transplant recipients, including one patient with histologically documented renal microthrombi; both patients were referred for plasma exchange. After the diagnosis of histoplasmosis, the treatment plan was changed to antifungal medications, reduced immuno‐suppression, and supportive care, with progressive resolution of TMA manifestations.

CONCLUSION: TMA occurs in transplant populations in association with infections, medications, and other factors. Appropriate management includes recognition and treatment of possible etiological factors. Disseminated histoplasmosis should be considered in transplant patients presenting with TMA.
Lower hemoglobin levels in human immunodeficiency virus–infected patients with a positive direct antiglobulin test (DAT): relationship with DAT strength and clinical stages
Authors: Lai Marco , Visconti Elena , D’Onofrio Giuseppe , Tamburrini Enrica , Cauda Roberto , Leone Giuseppe
Published: May 2006

BACKGROUND: There are conflicting opinions regarding the effect of positive direct antiglobulin test (DAT) on hemoglobin (Hb) levels in human immunodeficiency virus–infected (HIV+) patients.

STUDY DESIGN AND METHODS: A total of 166 samples from HIV+ outpatients were studied. The DAT was performed with the tube test and column agglutination technology (CAT).

RESULTS: The DAT was positive in 18.67 percent with the tube method and 33.73 percent with the CAT. Patients with DAT‐positive results showed lower Hb levels than DAT‐negative patients, 12.3 g per dL versus 14.3 g per dL (p = 0.0002). The univariate logistic regression enabled us to study the phenomenon better and fit the probability of having a DAT‐positive result on the basis of the Hb levels. The relationship between the CAT and the tube test when washing the red blood cells (RBC) at 4°C was stronger than when washing these at room temperature (φ = 0.8156; p = 0.000). The Hb levels were significantly lower in the positive DATs of Stage C (acquired immune deficiency syndrome [AIDS]) and Stage B (symptomatic non‐AIDS patients), which showed decreasing Hb values for increasing agglutination strengths (p = 0.000). Anemia was related with the DAT results (odds ratio [OR], 8.005; p = 0.000) but not to the AIDS condition (OR, 1.741; p = 0.221).

DISCUSSION: Our study indicates that the DAT‐positive results may be specifically related to lower Hb levels in HIV+ patients. The immunologic RBC clearance could be part of the anemic multifactorial condition in HIV+ patients.
Collaboration over Adaptation: The Case for Interoperable Communications in Homeland Security
Authors: Jenkins William O.
Published: May 2006

Analogizing the U.S. Department of Homeland Security to a corporate conglomerate consisting of multiple, formerly independent operating units with little in common and even less history of cooperation, this response to Professor Charles Wise prescribes the “bitter medicine” of interoperable communications. The critical function of assuring homeland security and disaster preparedness cannot depend on the uncertain trajectory of adaptive response.
Managing Public Service Contracts: Aligning Values, Institutions, and Markets
Authors: Brown Trevor L , Potoski Matthew , Van Slyke David M
Published: May 2006

The contracting of public services has been an integral part of public managers’ work for a long time, and it is here to stay. This essay sums up current research on the topic for busy practitioners and scholars. Where are we today with respect to the problems and pitfalls of contracting out, from balancing equity with efficiency to confronting the frequent problem of imperfect markets?
“E” the People: Do U.S. Municipal Government Web Sites Support Public Involvement?
Authors: Scott James K.
Published: May 2006

To what extent do local government Web sites support practical, meaningful public involvement? Fifteen years after the adoption and diffusion of the World Wide Web, the answer to this question remains cloudy and controversial. The promise—and peril—of Web‐based public involvement, known as e‐democracy, has been widely debated. Much of the debate has focused on theoretical abstractions or extrapolations of current political or technological trends. Empirical studies have been limited to reports on pilot projects, case studies, or special population surveys. This paper contributes to our empirical understanding of the question. It reports results of a recent comprehensive survey of official government Web sites in the principal cities of the 100 largest U.S. metropolitan areas. In particular, it examines whether and how U.S. city government Web sites facilitate users’ involvement in local public issues.
The Effects of E‐Government on Trust and Confidence in Government
Authors: Tolbert Caroline J. , Mossberger Karen
Published: May 2006

Trust in government has been declining for more than three decades now. E‐government has been proposed as a way to increase citizen trust in government and improve citizen evaluations of government generally. Using two‐stage models to analyze recent Pew survey data, this research explores the relationship between e‐government use, attitudes about e‐government, and trust in government. There is a statistically significant relationship between trust and use of a local government Web site, as well as other positive assessments of federal and local governments. The evidence suggests that e‐government can increase process‐based trust by improving interactions with citizens and perceptions of responsiveness. The findings are theoretically important for reconciling the conflicting research on the effects of e‐government and for understanding variations by level of government. Citizen attitudes toward government, including trust, are core concerns for democratic governance and public administration.
The Impact of Organizational Context and Information Technology on Employee Knowledge‐Sharing Capabilities
Authors: Kim Soonhee , Lee Hyangsoo
Published: May 2006

Sharing knowledge and information is an important factor in the discourses on electronic government, national security, and human capital management in public administration. This article analyzes the impact of organizational context and IT on employees’ perceptions of knowledge‐sharing capabilities in five public sector and five private sector organizations in South Korea. Social networks, centralization, performance‐based reward systems, employee usage of IT applications, and user‐friendly IT systems were found to significantly affect employee knowledge‐sharing capabilities in the organizations studied. For public sector employees, social networks, performance‐based reward systems, and employee usage of IT applications are all positively associated with high levels of employee knowledge‐sharing capabilities. Lessons and implications for knowledge‐sharing capabilities and management leadership in the public sector are presented.
The Challenging Business of Long‐Term Public–Private Partnerships: Reflections on Local Experience
Authors: Bloomfield Pamela
Published: May 2006

Many widely publicized arrangements bearing the popular “public–private partnership” label are complex, long‐term contracts between municipalities and private companies. In theory, these innovative contracts offer substantial public benefits, including improved service quality, risk sharing with the private sector, and cost savings. In practice, however, the challenges that long‐term contracts pose can undermine their successful implementation at the local level. Drawing on illustrative cases, this article explores some practical impediments to achieving market‐driven competition, equitable risk sharing, effective performance guarantees, and appropriate transparency in innovative long‐term contracts. It examines the inapplicability of the partnership model to most commercial transactions between government and business, the risks of uncontrollable circumstances, the impact of local resource constraints, and barriers to transparency in long‐term contracts. It concludes that local governments embarking on long‐term contracts must invest in specialized expertise, effective contract management, and strong governance structures.
Municipal Support for Social Entrepreneurship
Authors: Korosec Ronnie L. , Berman Evan M.
Published: May 2006

This study examines how cities help social entrepreneurship—the activity of private individuals and organizations taking initiative to address social challenges in their communities. Based on a national survey and in‐depth interviews among jurisdictions with populations over 50,000, the authors find that municipalities help social entrepreneurs by increasing awareness of social problems, and by helping them to acquire resources, coordinate with other organizations, and implement programs. Nearly three‐quarters of cities provide active or moderate support, which is positively associated with the perceived effectiveness of nonprofit organizations in their communities.
Morphology and Cell Division of Saudithrix terricola n. gen., n. sp., a Large, Stichotrich Ciliate from Saudi Arabia
Authors: BERGER HELMUT , AL‐RASHEID KHALED A. S. , FOISSNER WILHELM
Published: May 2006

ABSTRACT. The morphology and main ontogenetic traits of a new stichotrich ciliate, Saudithrix terricola Foissner, AL‐Rasheid and Berger n. gen., n. sp., from a terrestrial habitat in Saudi Arabia were investigated using live observation, protargol impregnation, and scanning electron microscopy. Saudithrix terricola is characterized by a large (200–350 × 70–150 μm), flexible body; an adoral zone formed like a three‐quarter circle; a sickle‐shaped buccal lip with a widened paroral forming a cyrtohymenid pattern with the endoral; 11 frontal and frontal‐ventral cirral rows (including right marginal rows) and one left marginal row covering the ventral side; two buccal cirri; six to nine transverse cirri; three dorsal kineties; and two macronuclear nodules. The resting cyst is about 85 μm across, has a smooth wall, and a fluffy mucous layer. Most cirral anlagen originate within the parental rows and are arranged side by side, the proximal portion of the adoral zone of membranelles is reorganized, and some parental dorsal bristles are maintained. Neither the morphological nor the ontogenetic data reveal the systematic position of Saudithrix within the stichotrichs. The term multicorona is introduced and describes a frontal ciliature composed of four or more cirral bows.
Effects of Stacking Scheme on Microwave Dielectric Characteristics of Ca(Mg1/3Nb2/3)O3–Ba(Zn1/3Nb2/3)O3 Layered Dielectric Resonators
Authors: Li Lei , Chen Xiang Ming
Published: May 2006

Ca(Mg1/3Nb2/3)O3 (CMN) and Ba(Zn1/3Nb2/3)O3 (BZN) ceramic disks were stacked with three stacking schemes, designated as CMN/BZN, CMN/BZN/CMN, and BZN/CMN/BZN, to yield layered dielectric resonators, and the microwave dielectric characteristics were evaluated with the TE01δ mode. Both experiments and finite element analysis showed that the microwave dielectric characteristics of the layered resonator were determined not only by the volume fraction of BZN but also by the stacking scheme. For each stacking scheme, a good combination of microwave dielectric characteristics with an effective dielectric constant of 34.33–34.52, a Q×f value of 58 800–62 080 GHz, and a near‐zero temperature coefficient of resonant frequency could be achieved by adjusting the volume fraction of BZN. The effects of the stacking scheme on the microwave dielectric characteristics of the temperature‐stable layered resonator were discussed by combining finite element analysis and dielectric composite models.
Rheology of Concentrated Suspensions Containing Weakly Attractive Alumina Nanoparticles
Authors: Studart André R. , Amstad Esther , Antoni Mathieu , Gauckler Ludwig J.
Published: May 2006

The use of nanoparticles for the fabrication of new functional ceramics and composites often requires the preparation of concentrated fluid suspensions. However, suspensions containing nanoparticles are limited in solids content because of the excluded volume formed by the dispersant adlayer around the particles. We investigated the effect of the adlayer thickness on the rheological behavior of suspensions containing model alumina nanoparticles, using dispersant molecules with deliberately tailored chain length. The apparent viscosity and yield stress of the particle suspensions were markedly decreased by increasing the dispersant length, mainly due to a reduction of the attractive forces among particles. Fluid suspensions with solids content up to 35 vol% were prepared in toluene using a dispersant length of 2.5 nm. Our experimental results and viscosity predictions based on a hard sphere model indicate that fluid suspensions with up to 43 vol% of 65 nm alumina particles could be prepared using an optimum dispersant length of about 3.6 nm.
Mechanical Properties of Dry‐Pressed Powder Compacts: Case Study on Alumina Nanoparticles
Authors: Kounga Njiwa A. B. , Aulbach E. , Rödel J. , Neubrand A.
Published: May 2006

Young's modulus and fracture toughness of dry‐pressed powder compacts of nanocrystalline alumina powders have been determined for different relative densities and average grain size. The powder with a grain size of 40 nm yielded a maximum Young's modulus of 15 GPa and a peak fracture toughness of 0.12 MPa·m1/2. These high values are rationalized using a model based on contact flattening between particle spheres, which allows a discussion of the influence of grain size and particle packing on the mechanical properties of green bodies.
A Glass–Ceramic Derived from High TiO2‐Containing Slag: Microstructural Development and Mechanical Behavior
Authors: Wu Jeremy P. , Rawlings Rees D. , Boccaccini Aldo R. , Dlouhy Ivo , Chlup Zdenek
Published: May 2006

A novel glass–ceramic material was developed from the melt of a TiO2‐containing iron‐making slag with additional waste glass. The high percentage (∼20 wt% TiO2) of this network‐modifying oxide has promoted a crystallization of the parent glass, resulting in a fine‐grained, homogeneous polycrystalline material with high mechanical properties (E=120 GPa, flexural strength=∼180 MPa, and Vickers hardness=7 GPa) after a heat treatment at 1100°C for 2 h. The room temperature and elevated temperature fracture toughness were also studied. The main crystalline phases of the glass–ceramic material were of the pyroxene series until heat‐treatment temperature reached 1000°C, at which titanium‐rich perovskite and armalcolite crystals became the dominant phases. The end material is high‐strength, aesthetically acceptable (metallic gray or opaque brown colored), and suitable for structural and architectural applications.
Conversion of SiO2 Diatom Frustules to BaTiO3 and SrTiO3
Authors: Dudley Shannon , Kalem Tugba , Akinc Mufit
Published: May 2006

Diatom frustules were used as bio‐templates to synthesize functional ceramics via solid–gas displacement reactions. Silica‐based frustules were exposed to TiF4 at 330°C to form TiOF2, which was later converted to TiO2 (anatase) by heat treatment in air at 600°C. The TiO2 frustules were then exposed to molten Ba(OH)2 or Sr(OH)2 to form BaTiO3 or SrTiO3, respectively. In both cases, near‐complete conversion was achieved while retaining the morphology of the original silica frustules. BaTiO3 and SrTiO3 frustules exhibit nearly phase pure, nanocrystalline perovskite structure.
Calcination Effects on the Properties of Gallium‐Doped Zinc Oxide Powders
Authors: Du Shangfeng , Tian Yajun , Liu Haidi , Liu Jian , Chen Yunfa
Published: May 2006

Highly conductive Gallium‐doped zinc oxide (Zn1−xGaxO) powder was prepared by calcining precursor that was synthesized from ZnSO4·7H2O, GaCl3, and NH4HCO3 by the co‐precipitation method. The effects of temperature, heating time, and atmosphere on the calcination process were studied, and we found that these factors are important to control the electrical conductivity, particle size, and agglomeration of Zn1−xGaxO powder. By studying these processing conditions, we found that the optimum one is calcining the precursor in H2 at 540°C for about 1.5 h, and the product has a specific surface area higher than 28 m2/g and volume resistivity lower than 16.8 Ω·cm. The chemistry details of the doping process were also discussed based on the experimental results.
Effect of Green Density on the Thermomechanical Properties of a Ceramic During Sintering
Authors: Schoenberg Sam E. , Green David J. , Messing Gary L.
Published: May 2006

The thermomechanical properties of a commercial barium titanate were experimentally or theoretically determined for samples with green densities ranging from 45% to 55%. For stresses less than 300 kPa, sample deformation was determined to be linear viscous for all three stages of sintering. The shrinkage rates at a given temperature can differ by up to ∼25% as the green density changes from 45% to 55%, and the maximum shrinkage rate increased with decreasing green density. The increase in shrinkage rate with lower green density samples persisted through the final sintering stage. The viscosity was determined by cyclic loading dilatometry to range from 5 to 6 GPa·s in the initial stage of sintering, to 2 GPa·s in the intermediate stage, and to increase to 10–20 GPa·s for all specimens in the final stage of sintering. Differences in the final‐stage viscosity were attributed to grain size differences. Relaxation times for the sintering body were estimated to be less than 1 s, indicating that viscous behavior is dominant throughout the sintering process.
Impression and Compression Creep of SiAlON Ceramics
Authors: Fox K. M. , Hellmann J. R. , Dickey E. C. , Green D. J. , Shelleman D. L. , Yeckley R. L.
Published: May 2006

Concurrent impression and uniaxial compression creep studies were performed on three Yb‐SiAlON materials. Stress exponents were approximately 1 in compression and 2 in impression. The higher stress exponents were due to the complex stress field in the impression creep test, which caused microstructural dilation. The dilated multi‐grain junctions also became filled with additional intergranular glassy phase. Focused ion beam milling and in situ lift‐out specimen preparation combined with transmission electron microscopy was successful in identifying microstructural changes after creep testing. These observations have important implications in the design of creep‐resistant materials in complex stress fields.
Ti3+‐Free Multicomponent Titanophosphate Glasses as Ecologically Sustainable Optical Glasses
Authors: Hashimoto Tadanori , Nasu Hiroyuki , Kamiya Kanichi
Published: May 2006

Ti3+‐free multicomponent titanophosphate glasses were developed as ecologically sustainable optical glasses. Especially, recent advances in the glasses as molding glass, athermal glass, nonlinear optical glass, and self‐cleaning glass were presented. The Ti3+‐free binary TiO2–P2O5 glasses containing TiO2 up to 74 mol% were prepared by melt quenching and long‐term post‐annealing around the glass transition temperature in the air, and possessed high transparency, high index, high dispersion, and low density. Li2O–ZnO–TiO2–P2O5 glasses have the lowest Tg (=560°C) among titanophosphate glasses, with high index (nd=1.8), and high dispersion (νd=22) being retained, while ZnO–TiO2–P2O5 glasses have the highest refractive index (nd=1.9) among glasses with Tg lower than 600°C. Thus, ZnO–TiO2–P2O5 and Li2O–ZnO–TiO2–P2O5 glasses can be expected as high‐index molding glasses. A very small temperature coefficient of refractive index, dn/dT, or very small temperature coefficient of optical path length, dS/dT, was obtained for K2O–TiO2–P2O5 glasses, meaning that they are considered as high‐index athermal glasses and athermal NLO glasses. Ag2O–TiO2–P2O5 glasses showed photocatalytic activity and photo‐induced hydrophilicity comparable with commercially available TiO2‐coated self‐cleaning glasses.
Capillary Porosity Depercolation/Repercolation in Hydrating Cement Pastes Via Low‐Temperature Calorimetry Measurements and CEMHYD3D Modeling
Authors: Bentz Dale P.
Published: May 2006

Capillary porosity percolation in a hydrating cement paste has a large influence on transport properties and durability. Percolation can be examined using low‐temperature calorimetry and using microstructure models. In this paper, the two approaches are compared for cement pastes with different water‐to‐cement ratios and exposed to various curing conditions. The influence of sealed curing is seen to be particularly important, as cement pastes that initially hydrate to depercolate the capillary pores may later undergo self‐desiccation and aging that repercolates them. Model predictions of the degree of hydration and the percolated capillary porosity volume fraction compare favorably with experiments.
Growth of ZnO Nanorods by the Chemical Solution Method with Assisted Electrical Field
Authors: Zhao Juan , Jin Zheng‐Guo , Li Tao , Liu Xiao‐Xin , Liu Zhi‐Feng
Published: May 2006

Zinc oxide (ZnO) nanorod arrays on the ZnO‐coated seed substrates were prepared by the solution chemical method from Zn(NO3)2/NaOH under an assisted electrical field. The influence of the electrical field on ZnO nanorod growth was primarily explored, and the positive effects of the electrical field were demonstrated by adding polyethylene glycol in growth solution. It has been proved that the electrical field enhances ion adsorption to the substrate and lowers the nucleation energy barrier by increasing charge intensity; meanwhile, it produces H+ through oxidation of OH− and increases properly the degree of solution supersaturation near the substrate surface. XRD results show that the nanorods grown under the electrical field primarily have a zincite structure. With increasing precursor concentration, the average diameter and length of ZnO nanorods increase. The maximum rod growth rate at a given concentration of Zn2+ ion occurs at a specific temperature.
Doped Lanthanum Gallate Film Solid Oxide Fuel Cells Fabricated On a Ni/YSZ Anode Support
Authors: He Tianmin , He Qiang , Pei Li , Ji Yuan , Liu Jiang
Published: May 2006

A colloidal deposition without any binder was developed to prepare a dense La0.8Sr0.2Ga0.85Mg0.15O3−δ (LSGM) film on porous NiO/YSZ substrates, using an incompletely crystallized LSGM powder as starting material. Both the dense LSGM film with a thickness of 15 μm and the required phase composition of the LSGM were achieved simultaneously by sintering at 1400°C for 6 h. The conductivity of the supported LSGM film attained 0.102 S/cm at 800°C, which was comparable with those of the self‐supported LSGM films. The maximum power density of the LSGM film cell was 480 at 800°C and 614 mW/cm2 at 850°C, respectively.
High‐Density Pressureless‐Sintered HfC‐Based Composites
Authors: Sciti Diletta , Silvestroni Laura , Bellosi Alida
Published: May 2006

Hafnium carbide (HfC)‐(5, 10, and 20 vol%) MoSi2 ceramics were pressureless sintered at 1950°C in an argon flux. The materials had nearly full density (96%–98%), with mean grain sizes in the range of 3–4 μm. Depending on the MoSi2 amount (5–20 vol%), the mechanical properties were in the following ranges: hardness 16–15 GPa, Young's modulus 434–385 GPa, fracture toughness 3.6–3.4 MPa·m1/2, and room‐temperature 4‐point flexural strength 465–383 MPa.
Optimization of a Nanoparticle Suspension for Freeze Casting
Authors: Lu Kathy , Kessler Chris S. , Davis Richey M.
Published: May 2006

Poly(acrylic acid) (PAA) dispersant concentration, suspension pH, and Al2O3 solids loading effects on PAA adsorption onto Al2O3 nanoparticles were studied; the stability and rheology of the Al2O3 nanoparticle suspensions were examined. The most desirable suspension conditions were 7.5–9.5 for pH and 2.00–2.25 wt% of Al2O3 for the PAA concentration. Electrical double‐layer thickness and PAA adsorption layer thickness comparison showed that electrosteric stabilization was dominant. 45.0 vol% Al2O3 solids loading can be achieved for freeze casting. The maximum solids loading was predicted to be 50.7 vol%. The freeze‐cast sample showed that pre‐rest before freezing was critical for achieving desirable microstructures.
Visualization of Subsurface Damage in Silicon Nitride from Grinding by a Plasma Etching and Dye Impregnation Method
Authors: Kanematsu Wataru
Published: May 2006

In order to develop a spatial morphology model of subsurface damage in grinding of hot‐pressed silicon nitride, the damage has been investigated using visualization techniques, plasma etching, and a dye impregnation method developed in our previous work. The plasma etching technique resolved subsurface damage formed by a single abrasive grit on a grinding wheel surface. The damage consists of a grain‐released area, which has an overall shape approximately that of a blade like a willow leaf, and a series of bow‐like crack series that appear repeatedly along the grit‐scratching direction. By coupling these results with previous conclusions about the geometry of the strength‐controlling cracks in a flexural test specimen, we were able to develop a spatial model of subsurface damage morphology. The most distinctive feature of the model is the absence of a transverse crack, whose presence is commonly accepted in existing work on subsurface damage by grinding. The applicability of the model to the fracture behavior of a longitudinally ground flexural test specimen was verified by fractography and dye impregnation.
Mineralizer‐Assisted Solvothermal Synthesis of Manganese Sulfide Crystallites
Authors: Zhu Xiaoyi , Ma Junfeng , Tao Jiantao , Zhou Jun , Zhao Zhongqiang , Xie Lijin , Tian Hua , Wang Yongqiang
Published: May 2006

Manganese sulfide (MnS) crystallites with varying morphology and polymorph can be synthesized via a solvothermal process assisted by mineralizers. It was found that KOH or KNO3 as a mineralizer played a key role in the crystallization and development of different kinds of MnS crystallites. Adding KOH in the solvothermal process resulted in the formation of α‐MnS crystallites, but γ‐MnS could be produced by introducing KNO3 as a mineralizer. The morphology control was also available.
Increased antidepressant use and fewer suicides in Jämtland county, Sweden, after a primary care educational programme on the treatment of depression
Authors: Henriksson S. , Isacsson G.
Published: May 2006

Objective:  To consider and evaluate a continuing medical education programme for general practitioners (GPs) on depression in Jämtland county, Sweden, inspired by the Gotland study.

Method:  Interactive seminars were conducted between 1995 and 2002 in Jämtland county. For evaluation, suicide rates and annual sales statistics of antidepressants were compared with national averages. Questionnaires were used for information about attitudes and prescribing habits.

Results:  The suicide rate in Jämtland decreased to the same level as the national average. The use of antidepressants increased from 25% below the Swedish average to the same level. The selective serotonin re‐uptake inhibitors (SSRIs) were preferred because of their tolerability. Suicide issues were considered to be most important in the management of depressed patients.

Conclusion:  A trend towards a greater prescription of antidepressants and fewer suicides after an educational programme on depression for GPs replicated the findings from the Gotland study. The educational programme will be conducted annually and could be a model for other regions.
Clinical outcome in bipolar disorder in a community‐based follow‐up study in Butajira, Ethiopia
Authors: Fekadu A. , Kebede D. , Alem A. , Fekadu D. , Mogga S. , Negash A. , Medhin G. , Beyero T. , Shibre T.
Published: May 2006

Objective:  To determine the clinical outcome of bipolar disorder in a developing country setup.

Method:  After assessing 68 378 individuals, aged 15–49 years, in a double‐sampling design in a rural community in Ethiopia, 312 patients with bipolar disorder were prospectively monitored with symptom rating scales and clinically for an average of 2.5 years.

Results:  Overall, 65.9% of the cohort experienced a relapse – 47.8% manic, 44.3% depressive and 7.7% mixed episodes – and 31.1% had persistent illness. Female gender predicted depressive relapse, while male gender predicted manic relapse. Being on psychotropic medication was associated with remission.

Conclusion:  This large community‐based study confirms the relapsing nature of bipolar disorder and a tendency for chronicity. This may be partly because of lack of appropriate interventions in this setting; however, it may also indicate the underlying severity of the disorder irrespective of setting.
Altered omega‐3 polyunsaturated fatty acid status in depressed post‐myocardial infarction patients
Authors: Schins A. , Crijns H. J. , Brummer R.‐J. M. , Wichers M. , Lousberg R. , Celis S. , Honig A.
Published: May 2006

Objective:  Lower levels of long‐chain omega‐3 polyunsaturated fatty acids (n‐3 LCPUFAs) and increased inflammation have been associated with both depressive disorder and myocardial infarction (MI). The present study investigated whether patients who develop depression post‐MI, have higher arachidonic acid/eicosapentanoic acid (AA/EPA) ratios than non‐depressed post‐MI patients and whether depressed post‐MI patients have signs of increased inflammation as measured by C‐reactive protein (CRP).

Method:  Serum AA/EPA ratio and plasma CRP levels were quantified in 50 post‐MI patients, of which 29 were depressed and 21 non‐depressed.

Results:  Compared with the non‐depressed group, depressed post‐MI patients had significantly higher AA/EPA ratios. No significant difference was observed in CRP levels.

Conclusion:  Depressed post‐MI patients had lower levels of n‐3 LCPUFAs as measured by mean AA/EPA ratio and no signs of increased inflammation as determined by CRP levels.
Impulsiveness in obsessive–compulsive disorder: results from a family study
Authors: Ettelt S. , Ruhrmann S. , Barnow S. , Buthz F. , Hochrein A. , Meyer K. , Kraft S. , Reck C. , Pukrop R. , Klosterkötter J. , Falkai P. , Maier W. , Wagner M. , Freyberger H. J. , Grabe H. J.
Published: May 2006

Objective:  Although obsessive–compulsive disorder (OCD) is usually conceptualized as an anxiety disorder some studies suggested it to be a deficit of impulse control. The purpose of this study was to assess impulsiveness in OCD families and compare it to control families.

Method:  Seventy cases and their 139 relatives were compared with 70 controls and their 134 relatives from a German family study on OCD (German Epidemiologic Network for OCD Studies). All subjects were interviewed and diagnosed according DSM‐IV criteria and were administered the Barratt Impulsiveness Scale (BIS) and PADUA‐Inventory to assess obsessive‐compulsive symptoms.

Results:  OCD subjects had significantly higher scores of cognitive impulsiveness. However, first‐degree relatives of OCD cases and of controls had comparable BIS‐11 scores. Significant associations of aggressive obsessions and checking with cognitive impulsiveness were found.

Conclusion:  OCD is a severe mental disorder that is characterized by a lack of cognitive inhibition. However, impulsiveness does not represent a familial trait in families of OCD subjects.