ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2863-2865 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of the carrier confinement on the output characteristics of GaInAs/AlGaAs lasers was investigated. To improve the carrier confinement, AlGaAs/GaAs short-period superlattices were used as quantum well barriers. In comparison to lasers with GaAs barriers the structures with the modified barriers show improved temperature properties at low threshold current densities without deterioration of the internal quantum efficiency (〉95%). High characteristic temperatures (T0) well above 300 K were measured between 20 and 75 °C and laser operation up to 238 °C could be achieved. The large improvement in T0 is mainly attributed to the reduced thermionic emission of carriers out of the quantum well due to the increased barrier height and the carrier reflection above the barrier by the short-period superlattice. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3031-3033 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Three-terminal Josephson junctions, the third terminal of which can be used to control the electronic properties of the device, are the key to a number of exciting device applications of high-Tc superconductors. To this end a novel device structure has been developed, which consists of an inverted metal-insulator-superconductor field-effect transistor into which a bicrystal grain boundary junction is embedded. These devices are excellent Josephson junctions as exemplified by their current–voltage characteristics and the magnetic field dependencies of the critical currents. The critical current of the junctions can be changed by 8% per volt applied to the gate electrode, the gate currents being negligible. Because they are sensitive to electric as well as magnetic fields, the junctions can be controlled by two independent inputs. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2289-2291 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The critical current Ic of YBa2Cu3O7−δ bicrystal grain boundary Josephson junctions (GBJs) have been measured in high magnetic fields up to B=12 T. Even at the highest applied magnetic fields, Ic varied periodically with varying magnetic field. By comparing the envelope of the measured Ic(B) dependencies to model calculations we obtain information on the spatial distribution of the supercurrent density jc on a length scale down to below 1 nm. Our analysis gives clear evidence that jc has spatial inhomogeneities on all length scales down to 1 nm with a probability distribution p(a) for the characteristic length scale a of the inhomogeneities. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 22 (1995), S. 15-32 
    ISSN: 1573-1111
    Keywords: β-Cyclodextrin ; triflumizole ; host-guest complex ; inclusion complex ; solvent accessible surface ; solubility enhancement ; hydrophobic effect ; dynamic Monte Carlo molecular docking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Solubility enhancement of the fungicide triflumicole byβ-cyclodextrin is explained using a thermodynamic approach. The influence of organic cosolvents on the overall equilibrium constants of triflumizole complexation withβ-cyclodextrin in aqueous solutions has been investigated. Their variance in mixed solvents is only partly explained by a competitive inclusion of substrate and cosolvent molecules inβ-cyclodextrin. The geometries of host-guest complexes have been estimated by molecular mechanics calculations. Their broad structural variety caused by the flexibility of host and guest molecules and different association possibilities of triflumizole have been analysed by a dynamic Monte Carlo docking method. The hydrophobic effect has been simulated by cominimization of the hydrophobic contributions to the solvation energy, calculated from the solvent accessible surface area of the complex and the conformational (potential) energy.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1573-1111
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We compare spectroscopic properties of higher order complexes of organic guests (e.g. naphthalene, phenols, indole, C60 fullerene) with cyclodextrins (CDx) to results of molecular modeling investigations. Naphthalene 1:2 complexes with α-CDx show high spectral resolution and peculiar triplet properties. Molecular simulations and calculation of the experimentally measured induced circular dichroism (ICD) provide detailed structural information.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of computer aided molecular design 13 (1999), S. 373-383 
    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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 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).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...