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  • 1
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    In:  Diplomarbeit, Institut für Geophysik der TU Clausthal
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  • 2
    ISSN: 1432-0878
    Keywords: Key words: Urothelium ; Tartrate-resistant acid phosphatase ; Nitric oxide synthase I ; Superoxide dismutase ; Immunocytochemistry ; Free radicals ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Three enzymes, viz., tartrate-resistant acid phosphatase (TRAP), nitric oxide synthase I (NOS-I), and superoxide dismutase (SOD), involved in the production and metabolism of free radicals or radical equivalents, were demonstrated by immunocytochemistry in the urothelium of the ureters of six patients of various ages. Two of these enzymes (TRAP and NOS-I) were colocalized in the most apical and lateral border of the superficial cells of the urothelium. In contrast, SOD showed a patchy or granular distribution within the supranuclear region of these cells. Intra- and subepithelial macrophages exhibited a weak TRAP, but no NOS-I or SOD, immune reaction. On the basis of the immunocytochemical findings, arguments in favor of a cytotoxic function of the superficial cells of the human urothelium are presented.
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  • 3
    ISSN: 0044-2313
    Keywords: Reaction of (tBu)2P—P=PX(tBu)2 (X = Br, Cl) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation and Reaction of the Phosphanylidene-phosphorane (tBu)2P—P = PX(tBu)2 (X = Br, Cl)The formation of (tBu)2P—P = P(Br)tBu2 1 from [(tBu)2P]2PLi and BrH2C—CH2Br begins with an exchange of Li against Br and is then determined by the migration of Br from the secondary P atom in [(tBu)2P]2PBr 6 to the primary P in 1. Similarly, (tBu)2P—P = PC1(tBu)2 2 is obtained starting from PCl3 and LiP(tBu)2. The formation of Phospanylidene - phosporane is not influenced by the choice o the halogene substituent, but the presence of the tBu groups is strongly required. (tBu)2P—P(Li)—P(SiMe3)2 e. g., yields (tBu)2P—P(br)—P(SiMe3)2 with BrH2C—CH2Br; however neither this nor (tBu)2P—P(Cl)—P(SiMe3)2 do rearrange to a Phosphanylidene-phosphorane. The F3C substituent could be neglected in this investigation as [(F3C)2P]2P—SiMe3 cannot be lithiated by means of BuLi.Compounds 1 and 2 display a charateristic temperature dependent behavior. While 1 at +20°C decomposes via the reactive intermediate (tBu)2P—P to from the cyclophosphanes P3[P(tBu)2]4, it gives crystals of [(tBu)2P]2P—p[P(tBu)2]2 at -20°C (from a solution in toluene).Reacting 1 with tBuLi produces (tBu)2P—P = P(H)tBu2 20 and (tBu)2P—P(H)—P(tBu)2 14. Initially, a transmetallation yield tBuBr and (tBu)2 P—P=Pli(tBu)2 21,then LiBr and isobutene are eliminated and 20 is formed which can rearrange to produce 14. Without the elimination of isobutene, 1 react with nBuLi to give 21 witch can be trapped with Me3SiCl as (tBu)2P—P(tBu)223. The main product in in this reaction is however [(tBu)2P]2P—nBu 22.
    Notes: Dei Bildung von (tBu)2P—P = P(Br)tBu2 1 aus [(tBu)2P]2PLi und BrH2C—CH2Br wird eingeleitet durch den Lithium-Brom-Austausch und ist bedingt durch die anschließende Br-wanderung vom sekundären P-Atom im [(tBu)2P]2PBr 6 zum primären P-Atom in 1 Entsprechend bildet sich (tBu)2P—P = P(CI)tBu2 2 bei de Synthese von [(tBu)2P]2PC1 7 aus PC13 und Lip(tBu)2. Der Reaktionsablauf it unabhängig von den Halogensubstituenten, wird aber entscheidend beeinflußt durch die tBu-Gruppen. So bildet (tBu)2P—P(Li)—P(SiMe3)2 mit BrH2C—CH2Br das (tBu)2P—P(br)—P(SiMe3)2, das aber ebenso wie (tBu)2P—P(CI)—P(SiMe3)2 keine Umlagerung zm Phosphanyliden-Phosphoran eingeht. Der Ein1Uß der F3C-Gruppe auf die Umlagerung war nicht zu untersuchen, da [(F3C)2P]2P—SIMe3 auch mit BuLi nicht in das lithiierte Derivat zu überführen ist.1 und 2 zeigen charakteristische Reaktionen in Abhängigkeit von der Temperatur. Während 1 bei +20°C über das Reaktiv (tBu)2P—P die Cyclophosphane P3[P(tBu)2]4 bildet, Kristallisiert aus den Lösungen von 1 (z. B. Toluol) bei -20°C [(tBu)2P]2P—P[P(tBu)2]2.Die Umsetzungen von 1 mit tBuLi führen zu (tBu)2P—P=(H)tBu2 20 und (tBu)2P—P(H)—P(tBu)2 14. Dei Reaktion wird durch die Umlithiierung zwischen 1 und tBuLi zu tBuBr und (tBu)2P—P=P(Li)tBu2 21 eingeleitet, der unter LiBr-Abspaltung und Isobuten-Eliminierung die Bildung von 20 folgt, das zu 14 umlagert. 21 wird durch Reaktion von 1 mit nBuLi faßbar [Ausblieben der Buten-Eliminierung], das mit Me3SiCl zu (tBu)2P—P(SiMe3)—P(tBu)2 23 abreagiert. Hauptprodukt der Umsetzung ist [(tBu)2P]2P-nBu 22.
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  • 4
    ISSN: 0044-2313
    Keywords: Chromium carbonyl complexes of the iPr2(Me3Si)P7: iPr2(H)P7[Cr(CO)5] ; iPr2(Me3Si)P7[Cr(CO)5] ; iPr2(H)P7[Cr(CO)5]2 ; iPr2(Me3Si)P7[Cr(CO)5][Cr(CO)4] (three isomers) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Complexes of P-rich Phosphanes and Silylphosphanes. VII Carbonyl Complexes of the Heptaphosphane(3) iPr2(Me3Si)P7From the reaction of iPr2(Me3Si)P7 1 with one equivalent of Cr(CO)5THF the yellow products iPr2(H)P7[Cr(CO)5] 2 and iPr2(Me3Si)P7[Cr(CO)5] 3 were isolated by column chromatography on silicagel. The P—H group in 2 results from a cleavage of the P—SiMe3 bond during chromatography. The Cr(CO)5 group in 2 is linked to an iPr—Pe atom, in 3 to the Me3Si—Pe atom of the P7 skeleton. The substituents do not force the formation of a single isomer; nevertheless 3 ist considerably favoured as compared to 2. From the reaction of 1 with 2 equivalents of Cr(CO)5THF the yellow iPr2(H)P7[Cr(CO)5]2 4 was isolated bearing one Cr(CO)5 group at an iPr—Pe atom, the other one at a Pb atom of the P7 skeleton.Compound 3 yields with Cr(CO)4NBD the red iPr2(Me3Si)P7[Cr(CO)5][Cr(CO)4] 5. Three isomers of 5 appear. Two Pe atoms of 5 are bridged by the Cr(CO)4 group, the third Pe atom is linked to the Cr(CO)5 ligand. iPr2(H)P7[Fe(CO)4] was isolated from the reaction of 1 with Fe2(CO)9. 31P NMR and MS data are reported.
    Notes: iPr2(Me3Si)P7 1 bildet mit einem Mol Cr(CO)5THF die gelben Verbindungen iPr2(H)P7[Cr(CO)5] 2 und iPr2(Me3Si)P7[Cr(CO)5] 3, die nach der chromatographischen Trennung auf einer Kieselgelsäure isoliert wurden. Die Ausbildung der P—H-Gruppe in 2 wird auf die Spaltung der P—SiMe3-Gruppe der Komplexverbindung bei der chromatographischen Trennung zurückgeführt. Die Cr(CO)5-Gruppe in 2 ist an die iPr—Pe-Gruppe, in 3 an die Me3Si—Pe-Gruppe des P7-Gerüstes gebunden. Die Substituenten beeinflussen die Komplexbildung nicht streng selektiv, jedoch ist Verbindung 3 gegenüber 2 deutlich begünstigt. Mit 2 Mol Cr(CO)5THF bildet 1das iPr2(H)P7[Cr(CO)5]2 4, in dem eine Cr(CO)5-Gruppe an eine iPr—Pe-Gruppe, die andere an ein Pb-Atom des P7-Gerüstes gebunden ist.Verbindung 3bildet mit Cr(CO)4NBD das rote iPr2(Me3Si)P7[Cr(CO)5][Cr(CO)4] 5, von dem drei Diastereomere auftreten. In 5 überbrückt die Cr(CO)4-Gruppe zwei Pe-Atome, an das dritte Pe-Atom ist die Cr(CO)5-Gruppe gebunden. Mit Fe2(CO)9 bildet 1das iPr2(H)P7[Fe(CO)4]. Es werden die Daten der 31P-NMR-Spektren und der massenspektrometrischen Untersuchung angegeben.
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  • 5
    ISSN: 0044-2313
    Keywords: Tetrakis(di-tert.-butylphosphino)diphosphane ; [(tBu)2P]2P—P[P(tBu)2]2 ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Structure of Tetrakis(di-tert.-butylphosphino)diphosphane [(tBu)2P]2P—P[P(tBu)2]2[(tBu)2P]2P—P[P(tBu)2]2 1 obtained at -20°C from a solution of (tBu)2P—P=P(Br)tBu2 forms yellow crystals (regular hexagons). 1 crystallizes monoclinic in the space group C2/c with a = 2145.6pm, b = 1137pm, c = 1696.1pm, β = 110.075° and Z = 4 formula units in the elementary cell. Due to high steric load the bond angles at the tertiary P atoms with δ = 115.7° are significantly larger than those at the primary P atoms with δ = 108.6°.
    Notes: [(tBu)2P]2P—P[P(tBu)2]2 1 sich aus (tBu)2P—P(Br)tBu2 (toluolische Lösung, -20°C) und fällt als gelbe Kristalle (regelmäßige Sechsecke) aus. 1 kristallisiert monoklin in der Raumgruppe C2/c mit den Gitterkonstanten a = 2145,6pm, b = 1137pm, c = 1696pm, β = 110,75°. Die Elementarzelle enthält 4 Formeleinheiten. Die Bindungswinkel an den tertiären P-Atomen mit δ = 115,7° sind infolge der hohen sterischen Belastung der tert. P-Atome gegenüber denen an den primären P-Atomen mit δ = 108,6° deutlich aufgeweitet.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0365-9496
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 7
    ISSN: 1573-4951
    Keywords: host–guest complexes ; molecular necklace ; molecular recognition ; molecular self-assembly ; molecular solvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper presents a computational study on the formation of a molecular necklace formed by specific threading of cyclodextrins (CDs) on block copolymers. Structural as well as energetic principles for the selective complexation of α- and β-cyclodextrin with poly(ethylene oxide)–poly(propylene oxide) block copolymers (PEO–PPO) are elucidated considering a diblock copolymer of equimolecular composition (PEO)4–(PPO)4 as guest. A non-statistical distribution of CDs, i.e. α-CDs primarily located on the PEO chain and β-CDs on PPO blocks of the polymer, is based on a variety of structural features and energetic preferences considering both potential as well as solvation energies. This selectivity becomes already obvious considering 1:1 complexes between PEO and PPO monomers and the two CDs, but is increasingly evident when calculating higher order ensembles. Besides the host–guest interaction, docking between CDs themselves is an important, also non-statistical, prerequisite for the self-assembly of highly ordered tubes. The formation of intermolecular hydrogen bonds between adjacent CDs in a tubular aggregate gives an important contribution to the overall stability of the molecular necklace. The net effect, based on the preferential interaction between host and guest as well as between the host molecules themselves, results in the formation of a stable, highly ordered macromolecular, multicomponent aggregate.
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  • 8
    ISSN: 1573-2932
    Keywords: bacterial sulfate reduction ; iron reduction ; sediment ; pore-water chemistry ; acidic mining lake ; stable sulfur isotopes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Chemical, microbiological and stable isotope analyses of sediments from an acidic mining lake were used to evaluate whether biogeochemical processes, such as iron and sulfate reduction, are extant, because such processes can potentially generate alkalinity. Sediment cores were sliced in cm intervals to achieve a high resolution for spatial distribution of organic and inorganic components. Iron, sulfur, carbon, nitrogen and phosphorus as well as the most probable number (MPN) of iron reducing bacteria, the amount of lipid phosphate and the stable isotope compositions of various sedimentary sulfur compounds were measured. Accumulation of degradable organic material, reduced mass fractions of iron, enhanced concentrations of lipid phosphate, high concentrations of DOC and ferrous iron in the pore water and a drastic change of sulfur isotope ratios in the upper 3 cm of the sediment all indicated a highly reactive zone of biogeochemical transformations. The data provide clear evidence for iron and sulfate reducing processes in the sediments that result in an increase of pH with depth.
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  • 9
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The effects of elevated atmospheric SO 4 2− deposition on S cycling in forest soils were assessed in an irrigation experiment using stable S isotopes. Over a period of 20 months, core lysimeters of five acidic forest soils from Southern Germany with different parent material and pedogenesis were irrigated with solutions chemically similar to canopy throughfall. Sulfate deposition in three experimental variants corresponded to 23, 42 and 87 kg S ha−1 yr−1. The SO 4 2− used for irrigation had aδ 34S ratio of +28.0‰ CDT (Canon Diablo Troilite standard), differing by more than +25‰ from natural and anthropogenic S in Southern Germany. A combination of chemical and isotopic analyses of soil and seepage water samples was used to elucidate the fluxes and transformations of simulated wet SO 4 2− deposition in each soil core. Retention of experimentally deposited S ranged from 57±5% in coarse-grained soils low in sesquioxides and clay, to 80±8% in loamy soils with high sesquioxide content. The sesquioxide content proved to be the major factor governing S retention. The ratio of S retained as inorganic SO 4 2− (mainly by adsorption) to that incorporated into organic compounds (presumably by microbial synthesis) ranged from 2 to 4. For the organic S pool, the amount of S retained as C-bonded S exceeded by far that immobilized as ester sulfate in four of the five soils. Application of34S-enriched SO 4 2− appears to be a suitable experimental tool to assess fluxes and transformations of deposited S in forest soils, if aerobic conditions are maintained. In contrast to radioactive S tracers, the concept should be applicable not only in laboratory and lysimeter experiments, but also in long term studies of whole forest ecosystems (e.g., experimental watersheds).
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  • 10
    ISSN: 1436-5073
    Keywords: infrared spectroscopy ; infrared reflection spectroscopy ; FT-IR ; conversion coating ; phosphate coating ; galvanized steel ; hopeite ; phosphophyllite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hopeite-type phosphate coatings in which zinc is replaced by other metals like nickel, manganese and magnesium are of great interest as conversion coatings on galvanized steel in the automotive and appliance industries. The analytical characterization of such coatings produced in special processes is not possible by XRD because the different types of hopeite are isomorphic. In this paper it is shown that the kind of metal substitution is responsible for certain specific features in the infrared reflection spectra. Furthermore the structural changes caused by dehydration due to heating of the coatings were studied and differences in the thermal stability of the different coatings thus could be observed.
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