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Expert Consensus Statement for Telepsychiatry and Attention Deficit Hyperactivity Disorder
- Jennifer Hong, Gregory W. Mattingly, Julie A. Carbray, Takesha V. Cooper, Robert L. Findling, Martin Gignac, Paul E. Glaser, Frank A. Lopez, Vladamir Maletic, Roger S. McIntyre, Adelaide S. Robb, Manpreet K. Singh, Mark Stein, Stephen M. Stahl
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- Journal:
- CNS Spectrums / Accepted manuscript
- Published online by Cambridge University Press:
- 20 May 2024, pp. 1-34
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4 Evaluating Plasma GFAP for the Detection of Alzheimer’s Disease Dementia
- Madeline Ally, Henrik Zetterberg, Kaj Blennow, Nicholas J. Ashton, Thomas K. Karikari, Hugo Aparicio, Michael A. Sugarman, Brandon Frank, Yorghos Tripodis, Ann C. McKee, Thor D. Stein, Brett Martin, Joseph N. Palmisano, Eric G. Steinberg, Irene Simkina, Lindsay Farrer, Gyungah Jun, Katherine W. Turk, Andrew E. Budson, Maureen K. O’Connor, Rhoda Au, Wei Qiao Qiu, Lee E. Goldstein, Ronald Killiany, Neil W. Kowall, Robert A. Stern, Jesse Mez, Michael L. Alosco
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 408-409
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Objective:
Blood-based biomarkers represent a scalable and accessible approach for the detection and monitoring of Alzheimer’s disease (AD). Plasma phosphorylated tau (p-tau) and neurofilament light (NfL) are validated biomarkers for the detection of tau and neurodegenerative brain changes in AD, respectively. There is now emphasis to expand beyond these markers to detect and provide insight into the pathophysiological processes of AD. To this end, a reactive astrocytic marker, namely plasma glial fibrillary acidic protein (GFAP), has been of interest. Yet, little is known about the relationship between plasma GFAP and AD. Here, we examined the association between plasma GFAP, diagnostic status, and neuropsychological test performance. Diagnostic accuracy of plasma GFAP was compared with plasma measures of p-tau181 and NfL.
Participants and Methods:This sample included 567 participants from the Boston University (BU) Alzheimer’s Disease Research Center (ADRC) Longitudinal Clinical Core Registry, including individuals with normal cognition (n=234), mild cognitive impairment (MCI) (n=180), and AD dementia (n=153). The sample included all participants who had a blood draw. Participants completed a comprehensive neuropsychological battery (sample sizes across tests varied due to missingness). Diagnoses were adjudicated during multidisciplinary diagnostic consensus conferences. Plasma samples were analyzed using the Simoa platform. Binary logistic regression analyses tested the association between GFAP levels and diagnostic status (i.e., cognitively impaired due to AD versus unimpaired), controlling for age, sex, race, education, and APOE e4 status. Area under the curve (AUC) statistics from receiver operating characteristics (ROC) using predicted probabilities from binary logistic regression examined the ability of plasma GFAP to discriminate diagnostic groups compared with plasma p-tau181 and NfL. Linear regression models tested the association between plasma GFAP and neuropsychological test performance, accounting for the above covariates.
Results:The mean (SD) age of the sample was 74.34 (7.54), 319 (56.3%) were female, 75 (13.2%) were Black, and 223 (39.3%) were APOE e4 carriers. Higher GFAP concentrations were associated with increased odds for having cognitive impairment (GFAP z-score transformed: OR=2.233, 95% CI [1.609, 3.099], p<0.001; non-z-transformed: OR=1.004, 95% CI [1.002, 1.006], p<0.001). ROC analyses, comprising of GFAP and the above covariates, showed plasma GFAP discriminated the cognitively impaired from unimpaired (AUC=0.75) and was similar, but slightly superior, to plasma p-tau181 (AUC=0.74) and plasma NfL (AUC=0.74). A joint panel of the plasma markers had greatest discrimination accuracy (AUC=0.76). Linear regression analyses showed that higher GFAP levels were associated with worse performance on neuropsychological tests assessing global cognition, attention, executive functioning, episodic memory, and language abilities (ps<0.001) as well as higher CDR Sum of Boxes (p<0.001).
Conclusions:Higher plasma GFAP levels differentiated participants with cognitive impairment from those with normal cognition and were associated with worse performance on all neuropsychological tests assessed. GFAP had similar accuracy in detecting those with cognitive impairment compared with p-tau181 and NfL, however, a panel of all three biomarkers was optimal. These results support the utility of plasma GFAP in AD detection and suggest the pathological processes it represents might play an integral role in the pathogenesis of AD.
5 Antemortem Plasma GFAP Predicts Alzheimer’s Disease Neuropathological Changes
- Madeline Ally, Henrik Zetterberg, Kaj Blennow, Nicholas J. Ashton, Thomas K. Karikari, Hugo Aparicio, Michael A. Sugarman, Brandon Frank, Yorghos Tripodis, Brett Martin, Joseph N. Palmisano, Eric G. Steinberg, Irene Simkina, Lindsay Farrer, Gyungah Jun, Katherine W. Turk, Andrew E. Budson, Maureen K. O’Connor, Rhoda Au, Wei Qiao Qiu, Lee E. Goldstein, Ronald Killiany, Neil W. Kowall, Robert A. Stern, Jesse Mez, Bertran R. Huber, Ann C. McKee, Thor D. Stein, Michael L. Alosco
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 409-410
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Objective:
Blood-based biomarkers offer a more feasible alternative to Alzheimer’s disease (AD) detection, management, and study of disease mechanisms than current in vivo measures. Given their novelty, these plasma biomarkers must be assessed against postmortem neuropathological outcomes for validation. Research has shown utility in plasma markers of the proposed AT(N) framework, however recent studies have stressed the importance of expanding this framework to include other pathways. There is promising data supporting the usefulness of plasma glial fibrillary acidic protein (GFAP) in AD, but GFAP-to-autopsy studies are limited. Here, we tested the association between plasma GFAP and AD-related neuropathological outcomes in participants from the Boston University (BU) Alzheimer’s Disease Research Center (ADRC).
Participants and Methods:This sample included 45 participants from the BU ADRC who had a plasma sample within 5 years of death and donated their brain for neuropathological examination. Most recent plasma samples were analyzed using the Simoa platform. Neuropathological examinations followed the National Alzheimer’s Coordinating Center procedures and diagnostic criteria. The NIA-Reagan Institute criteria were used for the neuropathological diagnosis of AD. Measures of GFAP were log-transformed. Binary logistic regression analyses tested the association between GFAP and autopsy-confirmed AD status, as well as with semi-quantitative ratings of regional atrophy (none/mild versus moderate/severe) using binary logistic regression. Ordinal logistic regression analyses tested the association between plasma GFAP and Braak stage and CERAD neuritic plaque score. Area under the curve (AUC) statistics from receiver operating characteristics (ROC) using predicted probabilities from binary logistic regression examined the ability of plasma GFAP to discriminate autopsy-confirmed AD status. All analyses controlled for sex, age at death, years between last blood draw and death, and APOE e4 status.
Results:Of the 45 brain donors, 29 (64.4%) had autopsy-confirmed AD. The mean (SD) age of the sample at the time of blood draw was 80.76 (8.58) and there were 2.80 (1.16) years between the last blood draw and death. The sample included 20 (44.4%) females, 41 (91.1%) were White, and 20 (44.4%) were APOE e4 carriers. Higher GFAP concentrations were associated with increased odds for having autopsy-confirmed AD (OR=14.12, 95% CI [2.00, 99.88], p=0.008). ROC analysis showed plasma GFAP accurately discriminated those with and without autopsy-confirmed AD on its own (AUC=0.75) and strengthened as the above covariates were added to the model (AUC=0.81). Increases in GFAP levels corresponded to increases in Braak stage (OR=2.39, 95% CI [0.71-4.07], p=0.005), but not CERAD ratings (OR=1.24, 95% CI [0.004, 2.49], p=0.051). Higher GFAP levels were associated with greater temporal lobe atrophy (OR=10.27, 95% CI [1.53,69.15], p=0.017), but this was not observed with any other regions.
Conclusions:The current results show that antemortem plasma GFAP is associated with non-specific AD neuropathological changes at autopsy. Plasma GFAP could be a useful and practical biomarker for assisting in the detection of AD-related changes, as well as for study of disease mechanisms.
Characterisation of age and polarity at onset in bipolar disorder
- Janos L. Kalman, Loes M. Olde Loohuis, Annabel Vreeker, Andrew McQuillin, Eli A. Stahl, Douglas Ruderfer, Maria Grigoroiu-Serbanescu, Georgia Panagiotaropoulou, Stephan Ripke, Tim B. Bigdeli, Frederike Stein, Tina Meller, Susanne Meinert, Helena Pelin, Fabian Streit, Sergi Papiol, Mark J. Adams, Rolf Adolfsson, Kristina Adorjan, Ingrid Agartz, Sofie R. Aminoff, Heike Anderson-Schmidt, Ole A. Andreassen, Raffaella Ardau, Jean-Michel Aubry, Ceylan Balaban, Nicholas Bass, Bernhard T. Baune, Frank Bellivier, Antoni Benabarre, Susanne Bengesser, Wade H Berrettini, Marco P. Boks, Evelyn J. Bromet, Katharina Brosch, Monika Budde, William Byerley, Pablo Cervantes, Catina Chillotti, Sven Cichon, Scott R. Clark, Ashley L. Comes, Aiden Corvin, William Coryell, Nick Craddock, David W. Craig, Paul E. Croarkin, Cristiana Cruceanu, Piotr M. Czerski, Nina Dalkner, Udo Dannlowski, Franziska Degenhardt, Maria Del Zompo, J. Raymond DePaulo, Srdjan Djurovic, Howard J. Edenberg, Mariam Al Eissa, Torbjørn Elvsåshagen, Bruno Etain, Ayman H. Fanous, Frederike Fellendorf, Alessia Fiorentino, Andreas J. Forstner, Mark A. Frye, Janice M. Fullerton, Katrin Gade, Julie Garnham, Elliot Gershon, Michael Gill, Fernando S. Goes, Katherine Gordon-Smith, Paul Grof, Jose Guzman-Parra, Tim Hahn, Roland Hasler, Maria Heilbronner, Urs Heilbronner, Stephane Jamain, Esther Jimenez, Ian Jones, Lisa Jones, Lina Jonsson, Rene S. Kahn, John R. Kelsoe, James L. Kennedy, Tilo Kircher, George Kirov, Sarah Kittel-Schneider, Farah Klöhn-Saghatolislam, James A. Knowles, Thorsten M. Kranz, Trine Vik Lagerberg, Mikael Landen, William B. Lawson, Marion Leboyer, Qingqin S. Li, Mario Maj, Dolores Malaspina, Mirko Manchia, Fermin Mayoral, Susan L. McElroy, Melvin G. McInnis, Andrew M. McIntosh, Helena Medeiros, Ingrid Melle, Vihra Milanova, Philip B. Mitchell, Palmiero Monteleone, Alessio Maria Monteleone, Markus M. Nöthen, Tomas Novak, John I. Nurnberger, Niamh O'Brien, Kevin S. O'Connell, Claire O'Donovan, Michael C. O'Donovan, Nils Opel, Abigail Ortiz, Michael J. Owen, Erik Pålsson, Carlos Pato, Michele T. Pato, Joanna Pawlak, Julia-Katharina Pfarr, Claudia Pisanu, James B. Potash, Mark H Rapaport, Daniela Reich-Erkelenz, Andreas Reif, Eva Reininghaus, Jonathan Repple, Hélène Richard-Lepouriel, Marcella Rietschel, Kai Ringwald, Gloria Roberts, Guy Rouleau, Sabrina Schaupp, William A Scheftner, Simon Schmitt, Peter R. Schofield, K. Oliver Schubert, Eva C. Schulte, Barbara Schweizer, Fanny Senner, Giovanni Severino, Sally Sharp, Claire Slaney, Olav B. Smeland, Janet L. Sobell, Alessio Squassina, Pavla Stopkova, John Strauss, Alfonso Tortorella, Gustavo Turecki, Joanna Twarowska-Hauser, Marin Veldic, Eduard Vieta, John B. Vincent, Wei Xu, Clement C. Zai, Peter P. Zandi, Psychiatric Genomics Consortium (PGC) Bipolar Disorder Working Group, International Consortium on Lithium Genetics (ConLiGen), Colombia-US Cross Disorder Collaboration in Psychiatric Genetics, Arianna Di Florio, Jordan W. Smoller, Joanna M. Biernacka, Francis J. McMahon, Martin Alda, Bertram Müller-Myhsok, Nikolaos Koutsouleris, Peter Falkai, Nelson B. Freimer, Till F.M. Andlauer, Thomas G. Schulze, Roel A. Ophoff
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- Journal:
- The British Journal of Psychiatry / Volume 219 / Issue 6 / December 2021
- Published online by Cambridge University Press:
- 25 August 2021, pp. 659-669
- Print publication:
- December 2021
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Background
Studying phenotypic and genetic characteristics of age at onset (AAO) and polarity at onset (PAO) in bipolar disorder can provide new insights into disease pathology and facilitate the development of screening tools.
AimsTo examine the genetic architecture of AAO and PAO and their association with bipolar disorder disease characteristics.
MethodGenome-wide association studies (GWASs) and polygenic score (PGS) analyses of AAO (n = 12 977) and PAO (n = 6773) were conducted in patients with bipolar disorder from 34 cohorts and a replication sample (n = 2237). The association of onset with disease characteristics was investigated in two of these cohorts.
ResultsEarlier AAO was associated with a higher probability of psychotic symptoms, suicidality, lower educational attainment, not living together and fewer episodes. Depressive onset correlated with suicidality and manic onset correlated with delusions and manic episodes. Systematic differences in AAO between cohorts and continents of origin were observed. This was also reflected in single-nucleotide variant-based heritability estimates, with higher heritabilities for stricter onset definitions. Increased PGS for autism spectrum disorder (β = −0.34 years, s.e. = 0.08), major depression (β = −0.34 years, s.e. = 0.08), schizophrenia (β = −0.39 years, s.e. = 0.08), and educational attainment (β = −0.31 years, s.e. = 0.08) were associated with an earlier AAO. The AAO GWAS identified one significant locus, but this finding did not replicate. Neither GWAS nor PGS analyses yielded significant associations with PAO.
ConclusionsAAO and PAO are associated with indicators of bipolar disorder severity. Individuals with an earlier onset show an increased polygenic liability for a broad spectrum of psychiatric traits. Systematic differences in AAO across cohorts, continents and phenotype definitions introduce significant heterogeneity, affecting analyses.
Composition dependence of hardness and elastic modulus of the cubic and hexagonal NbCo2 Laves phase polytypes studied by nanoindentation
- Wei Luo, Christoph Kirchlechner, Juan Li, Gerhard Dehm, Frank Stein
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- Journal:
- Journal of Materials Research / Volume 35 / Issue 2 / 28 January 2020
- Published online by Cambridge University Press:
- 28 January 2020, pp. 185-195
- Print publication:
- 28 January 2020
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Regarding the effect of composition on the mechanical properties of intermetallic phases such as Laves phases, there is conflicting information in the literature. Some authors observed defect hardening when deviating from stoichiometric Laves phase composition, whereas others find defect softening. Here, we present a systematic investigation of the defect state, hardness, and elastic modulus of cubic and hexagonal NbCo2 Laves phases as a function of crystal structure and composition. For this purpose, diffusion couples were prepared which exhibit diffusion layers of the cubic C15 and hexagonal C14 and C36 NbCo2 Laves phases, with concentration gradients covering their entire homogeneity ranges from 24 to 37 at.% Nb. Direct observations of dislocations and stacking faults in the diffusion layers as a function of composition were performed by electron channeling contrast imaging, and the hardness and elastic modulus were probed in the diffusion layers along the concentration gradients by nanoindentation.
Vegetation and Climate Changes during the Bronze and Iron Ages (∼3600–600 BCE) in the Southern Levant Based on Palynological Records
- Dafna Langgut, Israel Finkelstein, Thomas Litt, Frank Harald Neumann, Mordechai Stein
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- Journal:
- Radiocarbon / Volume 57 / Issue 2 / 2015
- Published online by Cambridge University Press:
- 09 February 2016, pp. 217-235
- Print publication:
- 2015
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This article presents the role of climate fluctuations in shaping southern Levantine human history from 3600 to 600 BCE (the Bronze and Iron Ages) as evidenced in palynological studies. This time interval is critical in the history of the region; it includes two phases of rise and decline of urban life, organization of the first territorial kingdoms, and domination of the area by great Ancient Near Eastern empires. The study is based on a comparison of several fossil pollen records that span a north-south transect of 220 km along the southern Levant: Birkat Ram in the northern Golan Heights, Sea of Galilee, and Ein Feshkha and Ze'elim Gully both on the western shore of the Dead Sea. The vegetation history and its climatic implications are as follows: during the Early Bronze Age I (∼3600–3000 BCE) climate conditions were wet; a minor reduction in humidity was documented during the Early Bronze Age II–III (∼3000–2500 BCE). The Intermediate Bronze Age (∼2500–1950 BCE) was characterized by moderate climate conditions, however, since ∼2000 BCE and during the Middle Bronze Age I (∼1950–1750 BCE) drier climate conditions were prevalent, while the Middle Bronze Age II–III (∼1750–1550 BCE) was comparably wet. Humid conditions continued in the early phases of the Late Bronze Age, while towards the end of the period and down to ∼1100 BCE the area features the driest climate conditions in the timespan reported here; this observation is based on the dramatic decrease in arboreal vegetation. During the period of ∼1100–750 BCE, which covers most of the Iron Age I (∼1150–950 BCE) and the Iron Age IIA (∼950–780 BCE), an increase in Mediterranean trees was documented, representing wetter climate conditions, which followed the severe dry phase of the end of the Late Bronze Age. The decrease in arboreal percentages, which characterize the Iron Age IIB (∼780–680 BCE) and Iron Age IIC (∼680–586 BCE), could have been caused by anthropogenic activity and/or might have derived from slightly drier climate conditions. Variations in the distribution of cultivated olive trees along the different periods resulted from human preference and/or changes in the available moisture.
Dead Sea Levels during the Bronze and Iron Ages
- Elisa Joy Kagan, Dafna Langgut, Elisabetta Boaretto, Frank Herald Neumann, Mordechai Stein
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- Journal:
- Radiocarbon / Volume 57 / Issue 2 / 2015
- Published online by Cambridge University Press:
- 09 February 2016, pp. 237-252
- Print publication:
- 2015
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The history of lake-level changes at the Dead Sea during the Holocene was determined mainly by radiocarbon dating of terrestrial organic debris. This article reviews the various studies that have been devoted over the past 2 decades to defining the Dead Sea levels during the Bronze and Iron Ages (≃5.5 to 2.5 ka cal BP) and adds new data and interpretation. In particular, we focus on research efforts devoted to refining the chronology of the sedimentary sequence in the Ze'elim Gully, a key site of paleoclimate investigation in the European Research Council project titled Reconstructing Ancient Israel. The Bronze and Iron Ages are characterized by significant changes in human culture, reflected in archaeological records in which sharp settlement oscillations over relatively short periods of time are evident. During the Early Bronze, Intermediate Bronze, Middle Bronze, and Late Bronze Ages, the Dead Sea saw significant level fluctuations, reaching in the Middle Bronze an elevation of ≃370 m below mean sea level (bmsl), and declining in the Late Bronze to below 414 m bmsl. At the end of the Late Bronze Age and upon the transition to the Iron Age, the lake recovered slightly and rose to ≃408 m bmsl. This recovery reflected the resumption of freshwater activity in the Judean Hills, which was likely accompanied by more favorable hydrological-environmental conditions that seem to have facilitated the wave of Iron Age settlement in the region.
Microstructure and Phase Transformation Temperatures of Two-Phase FeAl (B2) + FeAl2 Alloys
- Xiaolin Li, Martin Palm, Anke Scherf, Daniel Janda, Martin Heilmaier, Frank Stein
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1760 / 2015
- Published online by Cambridge University Press:
- 02 January 2015, mrsf14-1760-yy04-09
- Print publication:
- 2015
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Fe-Al alloys with about 55 to 65 at.% Al undergo a eutectoid transformation at 1095 °C: Fe5Al8 (ε) ↔ FeAl + FeAl2. Hence, as-cast Fe-Al alloys in this composition range show a very fine-scaled lamellar microstructure (average lamellar spacing below 500 nm) consisting of the two phases FeAl and FeAl2. The microstructure looks similar to the α2 + γ lamellar microstructure of Ti-Al-based alloys, which is known for having well-balanced properties in terms of creep, ductility and strength. However, there is limited knowledge about the properties of Fe-Al-based alloys in this composition range. In this study, a series of as-cast as well as heat-treated Fe-Al alloys with compositions between 57 and 63 at.% Al were investigated. The microstructures and crystal structures were analysed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The composition dependence of all transition temperatures was obtained by differential thermal analysis (DTA).
The Effect of Li on Intermetallic Fe-Al Alloys
- Xiaolin Li, Frank Stein, Martin Palm
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1516 / 2013
- Published online by Cambridge University Press:
- 29 November 2012, pp. 263-268
- Print publication:
- 2013
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A couple of FeAl alloys containing up to 1.4 at.% Li have been produced by vacuum induction melting. Though previous reports indicated a significant effect of Li on the properties of FeAl, no marked changes with respect to binary FeAl are observed. Specifically, no decrease of the lattice constant and no significant increase in ductility are found by alloying with Li. If at all, there is a slight increase of the lattice constant.
Compositional Dependence of the Compressive Yield Strength of Fe-Nb(-Al) and Co-Nb Laves Phases
- Simon Voß, Martin Palm, Frank Stein, Dierk Raabe
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1295 / 2011
- Published online by Cambridge University Press:
- 10 March 2011, mrsf10-1295-n06-02
- Print publication:
- 2011
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Large, defect-free single-phase samples of the hexagonal C14 NbFe2 and Nb(Fe,Al)2, and the cubic C15 NbCo2 Laves phases have been produced by a modified levitation melting technique. The compressive strength of NbFe2 and NbCo2 has been determined in dependence on the Nb content, that of Nb(Fe,Al)2 in dependence on the Al content. The binary phases did not show either a maximum (defect softening) or minimum (defect hardening) in strength when the Nb content was varied. Instead, for both phases an increase of the compressive strength with increasing Nb content is observed.
Contributors
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- By Rose Teteki Abbey, K. C. Abraham, David Tuesday Adamo, LeRoy H. Aden, Efrain Agosto, Victor Aguilan, Gillian T. W. Ahlgren, Charanjit Kaur AjitSingh, Dorothy B E A Akoto, Giuseppe Alberigo, Daniel E. Albrecht, Ruth Albrecht, Daniel O. Aleshire, Urs Altermatt, Anand Amaladass, Michael Amaladoss, James N. Amanze, Lesley G. Anderson, Thomas C. Anderson, Victor Anderson, Hope S. Antone, María Pilar Aquino, Paula Arai, Victorio Araya Guillén, S. Wesley Ariarajah, Ellen T. Armour, Brett Gregory Armstrong, Atsuhiro Asano, Naim Stifan Ateek, Mahmoud Ayoub, John Alembillah Azumah, Mercedes L. García Bachmann, Irena Backus, J. Wayne Baker, Mieke Bal, Lewis V. Baldwin, William Barbieri, António Barbosa da Silva, David Basinger, Bolaji Olukemi Bateye, Oswald Bayer, Daniel H. Bays, Rosalie Beck, Nancy Elizabeth Bedford, Guy-Thomas Bedouelle, Chorbishop Seely Beggiani, Wolfgang Behringer, Christopher M. Bellitto, Byard Bennett, Harold V. Bennett, Teresa Berger, Miguel A. Bernad, Henley Bernard, Alan E. Bernstein, Jon L. Berquist, Johannes Beutler, Ana María Bidegain, Matthew P. Binkewicz, Jennifer Bird, Joseph Blenkinsopp, Dmytro Bondarenko, Paulo Bonfatti, Riet en Pim Bons-Storm, Jessica A. Boon, Marcus J. Borg, Mark Bosco, Peter C. Bouteneff, François Bovon, William D. Bowman, Paul S. Boyer, David Brakke, Richard E. Brantley, Marcus Braybrooke, Ian Breward, Ênio José da Costa Brito, Jewel Spears Brooker, Johannes Brosseder, Nicholas Canfield Read Brown, Robert F. Brown, Pamela K. Brubaker, Walter Brueggemann, Bishop Colin O. Buchanan, Stanley M. Burgess, Amy Nelson Burnett, J. Patout Burns, David B. Burrell, David Buttrick, James P. Byrd, Lavinia Byrne, Gerado Caetano, Marcos Caldas, Alkiviadis Calivas, William J. Callahan, Salvatore Calomino, Euan K. Cameron, William S. Campbell, Marcelo Ayres Camurça, Daniel F. Caner, Paul E. Capetz, Carlos F. Cardoza-Orlandi, Patrick W. Carey, Barbara Carvill, Hal Cauthron, Subhadra Mitra Channa, Mark D. Chapman, James H. Charlesworth, Kenneth R. Chase, Chen Zemin, Luciano Chianeque, Philip Chia Phin Yin, Francisca H. Chimhanda, Daniel Chiquete, John T. Chirban, Soobin Choi, Robert Choquette, Mita Choudhury, Gerald Christianson, John Chryssavgis, Sejong Chun, Esther Chung-Kim, Charles M. A. Clark, Elizabeth A. Clark, Sathianathan Clarke, Fred Cloud, John B. Cobb, W. Owen Cole, John A Coleman, John J. Collins, Sylvia Collins-Mayo, Paul K. Conkin, Beth A. Conklin, Sean Connolly, Demetrios J. Constantelos, Michael A. Conway, Paula M. Cooey, Austin Cooper, Michael L. Cooper-White, Pamela Cooper-White, L. William Countryman, Sérgio Coutinho, Pamela Couture, Shannon Craigo-Snell, James L. Crenshaw, David Crowner, Humberto Horacio Cucchetti, Lawrence S. Cunningham, Elizabeth Mason Currier, Emmanuel Cutrone, Mary L. Daniel, David D. Daniels, Robert Darden, Rolf Darge, Isaiah Dau, Jeffry C. Davis, Jane Dawson, Valentin Dedji, John W. de Gruchy, Paul DeHart, Wendy J. Deichmann Edwards, Miguel A. De La Torre, George E. Demacopoulos, Thomas de Mayo, Leah DeVun, Beatriz de Vasconcellos Dias, Dennis C. Dickerson, John M. Dillon, Luis Miguel Donatello, Igor Dorfmann-Lazarev, Susanna Drake, Jonathan A. Draper, N. Dreher Martin, Otto Dreydoppel, Angelyn Dries, A. J. Droge, Francis X. D'Sa, Marilyn Dunn, Nicole Wilkinson Duran, Rifaat Ebied, Mark J. Edwards, William H. Edwards, Leonard H. Ehrlich, Nancy L. Eiesland, Martin Elbel, J. Harold Ellens, Stephen Ellingson, Marvin M. Ellison, Robert Ellsberg, Jean Bethke Elshtain, Eldon Jay Epp, Peter C. Erb, Tassilo Erhardt, Maria Erling, Noel Leo Erskine, Gillian R. Evans, Virginia Fabella, Michael A. Fahey, Edward Farley, Margaret A. Farley, Wendy Farley, Robert Fastiggi, Seena Fazel, Duncan S. Ferguson, Helwar Figueroa, Paul Corby Finney, Kyriaki Karidoyanes FitzGerald, Thomas E. FitzGerald, John R. Fitzmier, Marie Therese Flanagan, Sabina Flanagan, Claude Flipo, Ronald B. Flowers, Carole Fontaine, David Ford, Mary Ford, Stephanie A. Ford, Jim Forest, William Franke, Robert M. Franklin, Ruth Franzén, Edward H. Friedman, Samuel Frouisou, Lorelei F. Fuchs, Jojo M. Fung, Inger Furseth, Richard R. Gaillardetz, Brandon Gallaher, China Galland, Mark Galli, Ismael García, Tharscisse Gatwa, Jean-Marie Gaudeul, Luis María Gavilanes del Castillo, Pavel L. Gavrilyuk, Volney P. Gay, Metropolitan Athanasios Geevargis, Kondothra M. George, Mary Gerhart, Simon Gikandi, Maurice Gilbert, Michael J. Gillgannon, Verónica Giménez Beliveau, Terryl Givens, Beth Glazier-McDonald, Philip Gleason, Menghun Goh, Brian Golding, Bishop Hilario M. Gomez, Michelle A. Gonzalez, Donald K. Gorrell, Roy Gottfried, Tamara Grdzelidze, Joel B. Green, Niels Henrik Gregersen, Cristina Grenholm, Herbert Griffiths, Eric W. Gritsch, Erich S. Gruen, Christoffer H. Grundmann, Paul H. Gundani, Jon P. Gunnemann, Petre Guran, Vidar L. Haanes, Jeremiah M. Hackett, Getatchew Haile, Douglas John Hall, Nicholas Hammond, Daphne Hampson, Jehu J. Hanciles, Barry Hankins, Jennifer Haraguchi, Stanley S. Harakas, Anthony John Harding, Conrad L. Harkins, J. William Harmless, Marjory Harper, Amir Harrak, Joel F. Harrington, Mark W. Harris, Susan Ashbrook Harvey, Van A. Harvey, R. Chris Hassel, Jione Havea, Daniel Hawk, Diana L. Hayes, Leslie Hayes, Priscilla Hayner, S. Mark Heim, Simo Heininen, Richard P. Heitzenrater, Eila Helander, David Hempton, Scott H. Hendrix, Jan-Olav Henriksen, Gina Hens-Piazza, Carter Heyward, Nicholas J. Higham, David Hilliard, Norman A. Hjelm, Peter C. Hodgson, Arthur Holder, M. Jan Holton, Dwight N. Hopkins, Ronnie Po-chia Hsia, Po-Ho Huang, James Hudnut-Beumler, Jennifer S. Hughes, Leonard M. Hummel, Mary E. Hunt, Laennec Hurbon, Mark Hutchinson, Susan E. Hylen, Mary Beth Ingham, H. Larry Ingle, Dale T. Irvin, Jon Isaak, Paul John Isaak, Ada María Isasi-Díaz, Hans Raun Iversen, Margaret C. 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- Edited by Daniel Patte, Vanderbilt University, Tennessee
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- The Cambridge Dictionary of Christianity
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- 05 August 2012
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- 20 September 2010, pp xi-xliv
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Thermodynamic Re-Assessment of the Co-Nb System
- Cuiyun He, Frank Stein, M. Palm, Dierk Raabe
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- MRS Online Proceedings Library Archive / Volume 1128 / 2008
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- 01 February 2011, 1128-U05-30
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- 2008
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A new thermodynamic assessment of the Co-Nb system is presented. All experimental phase diagram data available from the literature have been critically reviewed and assessed using thermodynamic models for the Gibbs energies of the individual phases (Thermo-Calc). Compared to previous assessments more elaborate models for the description of the C14 and C36 Laves phases and for the μ phase were employed. Thereby a calculated phase diagram is obtained which satisfactorily agrees with the experimental data.
Microstructural Investigations of the Unusual Deformation Behavior of Nb2Co7
- Frank Stein, Martin Palm, Georg Frommeyer, Padam Jain, Sharvan Kumar, Lisa Siggelkow, Daniel Grüner, Guido Kreiner, Andreas Leineweber
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- MRS Online Proceedings Library Archive / Volume 1128 / 2008
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- 01 February 2011, 1128-U08-03
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- 2008
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Usually, single-phase intermetallics in bulk form can easily be crushed into powder by hammering. It was therefore quite a surprise when we found that a bulk sample of the monoclinic intermetallic compound Nb2Co7 could be extensively deformed at room temperature without shattering or fracturing. In a previous paper, results of microhardness, compression, tensile and bending tests were provided and discussed [1]. In order to understand the observed unusual deformation behavior of this intermetallic phase, its hitherto unknown crystal structure has been studied and the microstructure of undeformed and deformed samples has been analyzed in the present investigation by light-optical, scanning electron and transmission electron microscopy. Single-phase specimens deformed at very different strain rates (hammering and conventional compression testing) both show the occurrence of microcracks along grain boundaries which, in compression-deformed specimens, are strongly localized in extended shear bands oriented approximately 45° to the compression axis. The grains adjacent to the microcracks are heavily deformed whereas, away from the sheared regions, the samples remain free of any indication of plastic deformation.
An In-situ Electron Microscopy Study of Microstructural Evolution in a Co-NbCo2 Binary Alloy
- Sharvan Kumar, Padam Jain, Seong Woong Kim, Frank Stein, Martin Palm
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- MRS Online Proceedings Library Archive / Volume 1128 / 2008
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- 01 February 2011, 1128-U08-09
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- 2008
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The microstructure in a Co-rich, Co-15 at.% Nb alloy was characterized in the as-cast condition. A predominantly lamellar eutectic morphology composed of a Co-Nb solid solution and the C15 Laves phase NbCo2 was confirmed by transmission electron microscopy. The C15 phase was heavily twinned, with only one variant of twins being present in the individual lamella, while the Co solid solution had the face centered cubic structure. In-situ heating to 600°C in the microscope confirmed the decomposition of the metastable Laves phase into a fine equiaxed, ˜10-20 nm grain size microstructure, and the product phase is the monoclinic Nb2Co7. The individual grains appear faulted. The matrix solid solution retained the fcc structure and no change in structure was observed on cooling to room temperature. Heating to temperatures as high as 1130°C leads to rapid grain growth in the Nb2Co7 phase, and the nucleation and growth of a few new grains within the original grains; however, the reverse peritectoid transformation previously reported, was not observed.
Phase Equilibria in the Ternary Nb-Cr-Al System and Site Occupation in the Hexagonal C14 Laves Phase Nb(AlxCr1-x)2
- Oleg Prymak, Frank Stein, Alexander Kerkau, Alim Ormeci, Guido Michael Kreiner, Georg Frommeyer, Dierk Raabe
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- MRS Online Proceedings Library Archive / Volume 1128 / 2008
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- 01 February 2011, 1128-U08-11
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- 2008
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The ternary Nb-Cr-Al phase diagram exhibits extended phase fields of the cubic C15 and the hexagonal C14 Laves phases Nb(AlxCr1-x)2. A number of Nb-Cr-Al alloys were prepared by levitation melting and annealed at temperatures between 1150 and 1450 °C for up to 1500 h. Isothermal sections of the ternary Nb-Cr-Al phase diagram at 1150, 1300 and 1450 °C were obtained from electron probe microanalysis, X-ray powder diffraction and metallographic investigations in order to study the effect of Al on the stability and structure of the Laves phases. The C14 Laves phase in the Nb-Cr-Al system can dissolve up to 45 at.% Al by substituting Cr with Al on the two different crystallographic B-sites 2a and 6h of the C14 AB2 unit cell. The site occupations of the Al and Cr atoms on these two B-sites were determined by Rietveld analysis using the program FullProf. The experimental site occupation factors were compared to site occupation factors computed by a statistical mechanics approach based on first-principles electronic structure calculations. The experimental as well as the calculated site occupation factors indicate a preferred occupation of the 2a site by Al.
Ab Initio Study of Elastic Properties in Fe3Al-based Alloys
- Martin Friák, Johannes Deges, Frank Stein, Martin Palm, Georg Frommeyer, Jöerg Neugebauer
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- MRS Online Proceedings Library Archive / Volume 1128 / 2008
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- 01 February 2011, 1128-U02-04
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- 2008
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Fe3Al-based alloys constitute a very promising class of intermetallics with great potential for substituting austenitic- and martensitic steels at elevated temperatures. A wider use of these materials is partly hampered by their moderate ductility at ambient temperatures. Theoretical ab initio based calculations are becoming increasingly useful to materials scientists interested in designing new alloys. Such calculations are nowadays able to accurately predict basic material properties by needing only the atomic composition of the material. We have therefore employed this approach to explore (i) the relation between chemical composition and elastic constants, as well as (ii) the effect transition-metal substituents (Ti, W, V, Cr, Si) have on this relation. Using a scale-bridging approach we model the integral elastic response of Fe3Al-based polycrystals employing a combination of (i) single crystal elastic stiffness data determined by parameter-free first-principles calculations in combination with (ii) Hershey's homogenization model. The ab initio calculations employ density-functional theory (DFT) and the generalized gradient approximation (GGA). The thus determined elastic constants have been used to calculate the ratio between the bulk B and shear G moduli as an indication of brittle/ductile behavior. Based on this approach we have explored chemical trends in order to tailor mechanical properties. Using this information we have cast a selected set of Fe3Al-based ternary alloys, obtained for these the elastic constants by performing impulse excitation measurements at room as well as liquid nitrogen temperature and compared them with our theoretical results.
Structure and Disorder of the Laves Phases in the Co-Nb System
- Guido Michael Kreiner, Daniel Grüner, Yuri Grin, Frank Stein, Martin Palm, Alim Ormeci
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- MRS Online Proceedings Library Archive / Volume 1128 / 2008
- Published online by Cambridge University Press:
- 01 February 2011, 1128-U08-08
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- 2008
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A special feature of the Co-Nb system is the occurrence of the three different types of Laves phase with the ideal composition NbCo2. The C36 and the C14 phases are stable only at high temperatures and exhibit small homogeneity ranges, whereas the C15 phase forms with a broad homogeneity range enclosing the ideal composition. In case of C36 and Co-rich C15 the additional Co atoms substitute Nb atoms (Nb1-xCox)Co2. In the C36 phase the Co atoms preferentially occupy one of the two crystallographic Nb sites and are locally displaced by approx. 20 pm from the original Nb positions allowing the formation of favorable short Nb-Co bonds. In Nb-rich C14 only one of two crystallographic sites is occupied by Nb. The Kagomé layers of the Co atoms are distorted in the crystal structures of the hexagonal Laves phases. The deviation from the idealized crystal structure is mainly governed by the valence electron concentration. Quantum mechanical calculations show that the distortion is already an inherent feature of the point defect-free structures.
Strengthening of iron aluminide alloys for high-temperature applications
- Martin Palm, André Schneider, Frank Stein, Gerhard Sauthoff
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- MRS Online Proceedings Library Archive / Volume 842 / 2004
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- 26 February 2011, S1.7
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- 2004
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An overview is given on materials developments of ferritic and Fe3Al-based iron aluminium alloys with strengthening precipitate phases for high-temperature applications currently underway at the Max-Planck-Institut für Eisenforschung GmbH (MPIE). The development of high-temperature alloys for structural applications is to be focussed on optimisation of strength, creep and corrosion resistance at high temperatures and sufficient ductility at lower temperatures. This is discussed with respect to recent studies on Fe-Al-based alloys with strengthening precipitates, such as κ-phase Fe3AlCx, MC-carbides, Laves phase, and the B2-ordered intermetallic phase NiAl. The following alloy systems have been investigated: Fe-Al-X (X=C, Ti, Ta, Mo, Zr), Fe-Al-Ti-Nb, Fe-Al-Ni-Cr, and Fe-Al-M-C (M=Ti, V, Nb, Ta).
The investigations have been focussed on the microstructure, constitution, mechanical properties, and high-temperature corrosion behaviour of Fe-Al-based alloys with Al contents ranging from 10 to 30 at. %.