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  • 1
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    Drug-based modulation of endogenous stem cells promotes functional remyelination in vivo (2015)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2015-04-22
    Description: Multiple sclerosis involves an aberrant autoimmune response and progressive failure of remyelination in the central nervous system. Prevention of neural degeneration and subsequent disability requires remyelination through the generation of new oligodendrocytes, but current treatments exclusively target the immune system. Oligodendrocyte progenitor cells are stem cells in the central nervous system and the principal source of myelinating oligodendrocytes. These cells are abundant in demyelinated regions of patients with multiple sclerosis, yet fail to differentiate, thereby representing a cellular target for pharmacological intervention. To discover therapeutic compounds for enhancing myelination from endogenous oligodendrocyte progenitor cells, we screened a library of bioactive small molecules on mouse pluripotent epiblast stem-cell-derived oligodendrocyte progenitor cells. Here we show seven drugs function at nanomolar doses selectively to enhance the generation of mature oligodendrocytes from progenitor cells in vitro. Two drugs, miconazole and clobetasol, are effective in promoting precocious myelination in organotypic cerebellar slice cultures, and in vivo in early postnatal mouse pups. Systemic delivery of each of the two drugs significantly increases the number of new oligodendrocytes and enhances remyelination in a lysolecithin-induced mouse model of focal demyelination. Administering each of the two drugs at the peak of disease in an experimental autoimmune encephalomyelitis mouse model of chronic progressive multiple sclerosis results in striking reversal of disease severity. Immune response assays show that miconazole functions directly as a remyelinating drug with no effect on the immune system, whereas clobetasol is a potent immunosuppressant as well as a remyelinating agent. Mechanistic studies show that miconazole and clobetasol function in oligodendrocyte progenitor cells through mitogen-activated protein kinase and glucocorticoid receptor signalling, respectively. Furthermore, both drugs enhance the generation of human oligodendrocytes from human oligodendrocyte progenitor cells in vitro. Collectively, our results provide a rationale for testing miconazole and clobetasol, or structurally modified derivatives, to enhance remyelination in patients.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4528969/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4528969/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Najm, Fadi J -- Madhavan, Mayur -- Zaremba, Anita -- Shick, Elizabeth -- Karl, Robert T -- Factor, Daniel C -- Miller, Tyler E -- Nevin, Zachary S -- Kantor, Christopher -- Sargent, Alex -- Quick, Kevin L -- Schlatzer, Daniela M -- Tang, Hong -- Papoian, Ruben -- Brimacombe, Kyle R -- Shen, Min -- Boxer, Matthew B -- Jadhav, Ajit -- Robinson, Andrew P -- Podojil, Joseph R -- Miller, Stephen D -- Miller, Robert H -- Tesar, Paul J -- F30 CA183510/CA/NCI NIH HHS/ -- F30CA183510/CA/NCI NIH HHS/ -- NS026543/NS/NINDS NIH HHS/ -- NS030800/NS/NINDS NIH HHS/ -- NS085246/NS/NINDS NIH HHS/ -- P30 CA043703/CA/NCI NIH HHS/ -- P30CA043703/CA/NCI NIH HHS/ -- R01 NS026543/NS/NINDS NIH HHS/ -- R01 NS030800/NS/NINDS NIH HHS/ -- R21 NS085246/NS/NINDS NIH HHS/ -- T32 GM007250/GM/NIGMS NIH HHS/ -- T32 GM008056/GM/NIGMS NIH HHS/ -- T32GM008056/GM/NIGMS NIH HHS/ -- UL1 TR000439/TR/NCATS NIH HHS/ -- England -- Nature. 2015 Jun 11;522(7555):216-20. doi: 10.1038/nature14335. Epub 2015 Apr 20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA. ; Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA. ; 1] Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA [2] Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA [3] Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA. ; PerkinElmer, 940 Winter Street, Waltham, Massachusetts 02451, USA. ; Center for Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA. ; Drug Discovery Center, University of Cincinnati College of Medicine, Cincinnati, Ohio 45237, USA. ; National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, USA. ; Department of Microbiology-Immunology and Interdepartmental Immunobiology Center, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Avenue, Chicago, Illinois 60611, USA. ; 1] Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA [2] Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25896324" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Differentiation/drug effects ; Cerebellum/drug effects/metabolism/pathology ; Clobetasol/*pharmacology ; Demyelinating Diseases/drug therapy/metabolism/pathology ; Disease Models, Animal ; Encephalomyelitis, Autoimmune, Experimental/drug therapy/metabolism/pathology ; Female ; Germ Layers/drug effects/metabolism/pathology ; Humans ; Lysophosphatidylcholines ; MAP Kinase Signaling System ; Male ; Mice ; Miconazole/*pharmacology ; Mitogen-Activated Protein Kinases/metabolism ; Multiple Sclerosis/*drug therapy/*metabolism/pathology ; Myelin Sheath/*drug effects/*metabolism ; Oligodendroglia/cytology/drug effects/metabolism ; Phenotype ; Pluripotent Stem Cells/cytology/*drug effects/metabolism ; Receptors, Glucocorticoid/metabolism ; Regeneration/drug effects ; Tissue Culture Techniques
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    Infectious prions in the saliva and blood of deer with chronic wasting disease (2006)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2006-10-07
    Description: A critical concern in the transmission of prion diseases, including chronic wasting disease (CWD) of cervids, is the potential presence of prions in body fluids. To address this issue directly, we exposed cohorts of CWD-naive deer to saliva, blood, or urine and feces from CWD-positive deer. We found infectious prions capable of transmitting CWD in saliva (by the oral route) and in blood (by transfusion). The results help to explain the facile transmission of CWD among cervids and prompt caution concerning contact with body fluids in prion infections.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mathiason, Candace K -- Powers, Jenny G -- Dahmes, Sallie J -- Osborn, David A -- Miller, Karl V -- Warren, Robert J -- Mason, Gary L -- Hays, Sheila A -- Hayes-Klug, Jeanette -- Seelig, Davis M -- Wild, Margaret A -- Wolfe, Lisa L -- Spraker, Terry R -- Miller, Michael W -- Sigurdson, Christina J -- Telling, Glenn C -- Hoover, Edward A -- N01-AI-25491/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 2006 Oct 6;314(5796):133-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biological Sciences (CVMBS), Colorado State University (CSU), Fort Collins, CO 80523, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17023660" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain Chemistry ; Cohort Studies ; *Deer/blood ; Feces/chemistry ; Lymphoid Tissue/chemistry ; Prions/*analysis/*blood/urine ; Saliva/*chemistry ; Wasting Disease, Chronic/blood/*metabolism/*transmission
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Cell nonautonomous activation of flavin-containing monooxygenase promotes longevity and health span (2015)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2015-11-21
    Description: Stabilization of the hypoxia-inducible factor 1 (HIF-1) increases life span and health span in nematodes through an unknown mechanism. We report that neuronal stabilization of HIF-1 mediates these effects in Caenorhabditis elegans through a cell nonautonomous signal to the intestine, which results in activation of the xenobiotic detoxification enzyme flavin-containing monooxygenase-2 (FMO-2). This prolongevity signal requires the serotonin biosynthetic enzyme TPH-1 in neurons and the serotonin receptor SER-7 in the intestine. Intestinal FMO-2 is also activated by dietary restriction (DR) and is necessary for DR-mediated life-span extension, which suggests that this enzyme represents a point of convergence for two distinct longevity pathways. FMOs are conserved in eukaryotes and induced by multiple life span-extending interventions in mice, which suggests that these enzymes may play a critical role in promoting health and longevity across phyla.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Leiser, Scott F -- Miller, Hillary -- Rossner, Ryan -- Fletcher, Marissa -- Leonard, Alison -- Primitivo, Melissa -- Rintala, Nicholas -- Ramos, Fresnida J -- Miller, Dana L -- Kaeberlein, Matt -- P30AG013280/AG/NIA NIH HHS/ -- R00AGA0033050/PHS HHS/ -- R01AG038518/AG/NIA NIH HHS/ -- T32AG000057/AG/NIA NIH HHS/ -- New York, N.Y. -- Science. 2015 Dec 11;350(6266):1375-8. doi: 10.1126/science.aac9257. Epub 2015 Nov 19.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, University of Washington, Seattle, WA 98195, USA. ; Department of Biochemistry, University of Washington, Seattle, WA 98195, USA. ; Department of Pathology, University of Washington, Seattle, WA 98195, USA. kaeber@uw.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26586189" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Basic Helix-Loop-Helix Transcription Factors/metabolism ; Caenorhabditis elegans/genetics/metabolism/*physiology ; Caenorhabditis elegans Proteins/chemistry/genetics/metabolism/*physiology ; Diet ; Intestines/*enzymology ; Longevity/genetics/*physiology ; Mice ; Neurons/*metabolism ; Oxygenases/genetics/*physiology ; Protein Stability ; RNA Interference ; Receptors, Serotonin/metabolism ; Signal Transduction ; Transcription Factors/chemistry/*metabolism ; Tryptophan Hydroxylase/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
    Electronic Resource
    Electronic Resource
    Collapse of species boundaries in the wild potatoSolanum brevicaule complex (Solanaceae, S. sect.Petota): Molecular data (1999)
    Springer
    Plant systematics and evolution 214 (1999), S. 103-130 
    Details
    ISSN: 1615-6110
    Keywords: Solanaceae ; sect.Petota ; Solanum brevicaule ; Domestication ; hybridization ; potatoes ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheSolanum brevicaule complex is a group of morphologically very similar wild and cultivated potato taxa (Solanum sect.Petota). This study uses single to low-copy nuclear RFLPs and RAPDs to investigate their species boundaries and relationships. Cladistic analyses of both data sets are largely concordant with each other and with a recently published phenetic analyses of the same accessions using morphology. All three data sets separate members of the complex into populations from Peru and immediately adjacent northwestern Bolivia, including most cultivated species accessions, and populations from northwestern Bolivia to Argentina. The molecular results suggest that the complex is paraphyletic as currently circumscribed. Many species of theS. brevicaule complex should be relegated to synonymy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00985734
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  • 5
    Electronic Resource
    Electronic Resource
    Über Dimethylaminophenyl-pyrazolyl-und 1-.2.3-triazolyl-carbinole (1962)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 95 (1962), S. 222-227 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: p-Dimethylaminophenyl-pyrazolyl-(4)- und -(5)-carbinole sind im Gegensatz zu den entsprechenden Pyrrylderivaten nicht zur Bildung farbiger Methenverbindungen oder Kationen befähigt. Bis-[p-dimethylamino-phenyl]-pyrazolylcarbinole und Bis-[p-dimethylamino-phenyl]-[1.2.3-triazolyl]-carbinole bilden Farbsalze vom Malachitgrüntyp. Die Lage ihrer x-Banden erlaubt eine Abschätzung des Elektronendrucks, den die heterocyclischen Liganden an verschiedenen Stellen ihrer Ringsysteme aufweisen.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19620950135
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  • 6
    Electronic Resource
    Electronic Resource
    Anwendungen der 13C-NMR-Spektroskopie, XXVII. Die Aktivierungsparameter der Cope-Umlagerung von Semibullvalen, 1,5-Dimethylsemibullvalen und 2,6-Dibrom-1,5-dimethylsemibullvalen (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 925-931 
    Details
    ISSN: 0009-2940
    Keywords: Semibullvalene ; Cope rearrangement ; Dynamic NMR, 13C NMR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Applications of 13C-NMR Spectroscopy, XXVII. - Activation Parameters off the Cope Rearrangements of semibullvalene, 1,5-Dimethylsemibullvalene, and 2,6-Dibromo-1,5dimethylsemibullvaleneThe kinetics of the degenerate Cope rearrangements of the title compounds were measured by dynamic 13C-NMR spectroscopy. The rate constants derived from the changes in NMR lineshape yielded, on the basis of the Eyring equation, the following activation parameters: semibullvalene (1) ΔH≠ = 5.2 kcal mol-1, ΔS≠ = -3.2 cal K-1 mol-1, ΔG≠298 = 6.2 kcal mol-1; 1,5-dimethylsemibullvalene (2) ΔH≠ = 4.5 kcal mol-1, ΔS≠ = -1.6 cal K-1 mol-1, ΔG≠298 = 5.0 kcal mol-1; 2,6-dibromo-1,5-dimethylsemibullvalene (3) ΔH≠ = 7.5 kcal mol-1, ΔS≠ ≈ 0 cal K-1 mol-1, ΔG≠298 = 7.4 kcal mol-1. The substituent effects are compared with those of other substituted semibullvalenes and are discussed with respect to the nature of the transition state for the Cope rearrangement of bridged homotropilidenes. The barrier for 2 is the lowest measured so far by dynamic NMR spectroscopy.
    Notes: Die Kinetik der entarteten Cope-Umlagerungen der Titelverbindungen wurden mittels dynamischer 13C-NMR-Spectroskopie gemessen. Die aus den NMR-Linienformänderungen abgeleiteten Reaktionsgeschwindigkeitskonstanten k lieferten auf der Basis der Eyring-Gleichung folgende Aktivierungsparameter: Semibullvalen (1) ΔH≠ = 5.2 kcal mol-1, ΔS≠ = -3.2 cal K-1 mol-1, ΔG≠298 = 6.2 kcal mol-1; 1,5-Dimethylsemibullvalen (2) ΔH≠ = 4.5 kcal mol-1, ΔS≠ = -1.6 cal K-1 mol-1, ΔG≠298 = 5.0 kcal mol-1; 2,6-Dibrom-1,5-dimethylsemibullvalen (3) ΔH≠ = 7.5 kcal mol-1, ΔS≠ ≈ 0 cal K-1 mol-1, ΔG≠298 = 7.4 kcal mol-1. Die Substituenteneffekte werden mit denen anderer substituierter Semibullvalene verglichen und im Hinblick auf die Natur des Übergangszustandes der Cope-Umlagerung in überbrückten Homotropilidenen diskutiert. Die für 2 bestimmte Barriere ist die niedrigste, die bisher mit der dynamischen NMR-Spektroskopie gemessen wurden.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220522
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  • 7
    Electronic Resource
    Electronic Resource
    Über Mannichbasen, VIII. Die Struktur von Produkten der Betti-Reaktion mit Ammoniak (1974)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 107 (1974), S. 2675-2682 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Mannich Bases, VIII. The Structure of Products from the Betti Reaction with AmmoniaThe Betti reaction of 8-hydroxyquinoline, benzaldehyde, and ammonia gives no dihydro-oxazine, but a hydroxyimine derivative (6). Therefore the acylation forms the N-acyl-Mannich base (8). The analogous reaction with amides instead of ammonia could not be repeated by following the literature, it occurs only under more rigorous conditions. The Betti product of 2-naphthol, benzaldehyde, and ammonia represents in solution a mixture of two dihydro-oxazine stereoisomers (3) besides the hydroxyimine compound (4).
    Notes: Die Betti-Reaktion von 8-Hydroxychinolin, Benzaldehyd und Ammoniak liefert kein Dihydro-oxazin-, sondern ein Hydroxyimin-Derivat (6). Die Acylierung führt daher zur N-Acyl-Mannichbase (8). Die analoge Umsetzung mit Amiden anstelle von Ammoniak konnte nach der Literaturvorschrift nicht reproduziert werden; sie findet erst unter verschärften Bedingungen statt. Bei dem Betti-Produkt aus 2-Naphthol, Benzaldehyd und Ammoniak liegt in Lösung ein Gemisch von zwei Dihydrooxazin-Stereoisomeren (3) neben der Hydroxyimin-Verbindung (4) vor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19741070828
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  • 8
    Electronic Resource
    Electronic Resource
    Die quantitative Bestimmung des Cadmiums (1901)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 28 (1901), S. 233-241 
    Details
    ISSN: 0863-1778
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19010280118
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  • 9
    Electronic Resource
    Electronic Resource
    Die Kristall- und Molekülstruktur von Mangan(VII)-oxid (1988)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 558 (1988), S. 7-20 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal and Molecular Structure of Manganese (VII) OxideMn2O7 crystallizes in the monoclinic space group P21/c with a = 679.56 pm, b = 1668.7 pm, c = 945.4 pm, β = 100.20°, Z = 8. The Mn2O7 molecule consists of cornersharing pairs of MnO4 tetrahedra; the bridging Mn—O—Mn angle is 120.7°. The Mn—O bond lengths are 177.0 pm (bridge), 2 × 160.0 pm and 158.5 pm in the MnO4 tetrahedron.In the crystal the Mn2O7 molecules are packed in a way to yield the arrangement of a cubic close packing for the O atoms. Formally Mn2O7 can be described as a defect-anti-type of CaF2.We compare the geometrical properties of Mn2O7 with other molecular structures with an emphasis on the difference of structure and bonding between Mn2O7 and Tc2O7.
    Notes: Mn2O7 kristallisiert monoklin mit a = 679,56 pm, b = 1668,7 pm, c = 945,4 pm, β = 100,20°, Z = 8 in der Raumgruppe P21/c. Das Mn2O7-Molekül besteht aus zwei über ein verbrückendes O-Atom verknüpften MnO4-Tetraedern; der Brückenwinkel Mn—O—Mn beträgt 120,7°. Die Bindungsabstände Mn—O sind 177,0 pm (Brücke) sowie 2 × 160,0 pm und 158,5 pm im MnO4-Tetraeder.Im festen Zustand sind die Mn2O7-Moleküle in einer Weise gepackt, daß die Anordnung der O-Atome im Kristall einer kubisch dichtesten Kugelpackung entspricht, d. h. Mn2O7 läßt sich einfach als Defekt-anti-CaF2-Typ beschreiben.Die geometrischen Eigenschaften von Mn2O7 werden anderen Molekülstrukturen gegenüber-gestellt; insbesondere werden Mn2O7 und Tc2O7 bezüglich Struktur und Bindung verglichen.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19885580101
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  • 10
    Electronic Resource
    Electronic Resource
    LnHal2Hn  -  Neue Phasen in den ternären Systemen Ln/Hal/H (Ln = Lanthanoid, Hal = Br, I) III. Physikalische Eigenschaften (1992)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 618 (1992), S. 98-106 
    Details
    ISSN: 0044-2313
    Keywords: Rare earth hydride halides ; ir, uv/vis, photoelectron spectra ; magnetism ; electrical properties ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: LnHal2Hn - New Phases in the Ternary System Ln/Hal/H (Ln = Lanthanoid, Hal = Br, I) 111. Physical PropertiesIR and diffuse reflectance spectra, magnetic susceptibility and electrical resistance as well as photo-electron spectra of GdI2Hn and CeI2Hn (n ≦ 1) are reported. GdI2Hn samples with 0 〈 n 5 1 are insulators or semiconductors. Compounds with n = 1 are colourless, with n 〈 1 blue transparent. Phases with n 〈 0.9 show metallic lustre. This feature and the electrical properties can be understood on the basis of the electronic structure (Extended Hückel calculations, photoelectron- and reflectance spectroscopy). For n ≠ 1, in contrast to the stoichiometric hydride halides, bands approx. 1 eV below the Fermi edge are populated. With decreasing H content they broaden and the density of states increases. CeI2Hn exhibits a metal-to-semiconductor transition for n = 0.33. According to the susceptibility measurements the ferromagnetic order of GdI2 successively is suppressed by the incorporation of hydrogen. Simultaneously, correlated regions with spontaneous magnetization are maintained. Temperature dependent X-ray diffraction measurements also indicate the existance of such clusters.
    Notes: Es wird über IR- und diffuse Reflexionsspektroskopie, magnetische Suszeptibilitäts- und elektrische Widerstandsmessungen sowie Photoelektronenspektroskopie an GdI2Hn und Cel2Hn und Cel2Hn (n ≦ 1) berichtet. GdI2Hn-Proben mit 0 〈 n ≦ 1 sind Isolatoren bzw. Halbleiter. Verbindungen mit n = 1 sind farblos, mit n 〈 1 blau transparent und n 〈 0,9 zunehmend metallisch glänzend. Dies und die elektrischen Eigenschaften sind mit der elektronischen Struktur (Extended-Hückel-Rechnungen, Photoelektronen- und Reflexionsspektren) interpretierbar: Gegenüber den stöchiometrischen Hydridhalogeniden werden bei n ≠ 1 ca. 1 eV unterhalb der Fermikante Bänder besetzt, die sich mit sinkendem H-Gehalt zunehmend verbreitern und deren Zustandsdichte sich erhöht. CeI2Hn zeigt einen Metall-Halbleiter-Übergang bei n ∼ 0,33.Suszeptibilitätsmessungen zufolge wird die ferromagnetische Ordnung in GdI2 durch den Einbau von Wasserstoff sukzessive unterdrückt. Dies geschieht unter Erhalt von korrelierten Bereichen, die ferromagnetische Spontanmagnetisierung aufweisen. Für die Existenz solcher Cluster sprechen auch die Ergebnisse temperaturabhängiger Röntgendiffraktometrie.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19926180118
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