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  • 1
    ISSN: 1420-9136
    Keywords: High pressure ; pressure calibration ; ZnTe ; synchrotron X-ray source ; DIA type cubic anvil apparatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Pressure behavior of ZnTe at room temperature was studied using an X-ray energy dispersive method on a DIA type cubic anvil apparatus (SAM-85) at NSLS-X17B1. By using powdered polyethylene, the sample and NaCl for a pressure scale were held under quasihydrostatic conditions, which were confirmed by X-ray diffraction method. Two high-pressure phase transitions were confirmed using X-ray powder diffraction simultaneously with electrical resistance measurements. The phase transition pressures under quasihydrostatic conditions were determined to be 9.6 GPa, at which the resistance increased, and 12.0 GPa, which was the midpoint of a large resistance decrease. Errors in the pressure determinations were estimated to be less than 0.2 GPa. These pressure values may depend on grain size and anisotropic stress effects on the calibrant. From X-ray observation of ZnTe, the bulk modulus of the zinc blende structure was calculated to beK 0=51(3) GPa andK 0 ′ =3.6(0.8), and the first transition at 9.6 GPa was found to have about 9% volume change. It was consistent with an anomaly in the pressure generating curves.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 146 (1996), S. 533-549 
    ISSN: 1420-9136
    Keywords: Lower mantle ; seismic tomography ; thermoelasticiti ; composition models ; geodynamics ; shear modulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We estimate (ϖμ/ϖT) P of the lower mantle at seismic frequencies using two distinct approaches by combining ambient laboratory measurements on lower mantle minerals with seismic data. In the first approach, an upper bound is estimated for |(ϖμ/ϖT) P | by comparing the shear modulus (μ) profile of PREM with laboratory room-temperature data of μ extrapolated to high pressures. The second approach employs a seismic tomography constraint (ϖ lnV S /ϖ lnV P ) P =1.8–2, which directly relates (ϖμ/ϖT) P with (ϖK S /ϖT) P . An average (ϖK S /ϖT) P can be obtained by comparing the well-established room-temperature compression data for lower mantle minerals with theK S profile of PREM along several possible adiabats. Both (ϖK S /ϖT) and (ϖμ/ϖT) depend on silicon content [or (Mg+Fe)/Sil of the model. For various compositions, the two approaches predict rather distinct (ϖμ/ϖT) P vs. (ϖK S /ϖT) P curves, which intersect at a composition similar to pyrolite with (ϖμ/ϖT) P =−0.02 to −0.035 and (ϖK S /ϖT) P =−0.015 to −0.020 GPa/K. The pure perovskite model, on the other hand, yields grossly inconsistent results using the two approaches. We conclude that both vertical and lateral variations in seismic velocities are consistent with variation due to pressure, temperature, and phase transformations of a uniform composition. Additional physical properties of a pyrolite lower mantle are further predicted. Lateral temperature variations are predicted to be about 100–250 K, and the ratio of (ϖ lnp/ϖ lnV S ) P around 0.13 and 0.26. All of these parameters increase slightly with depth if the ratio of (ϖ lnV S /ϖ lnV P ) P remains constant throughout the lower mantle. These predicted values are in excellent agreement with geodynamic analyses, in which the ratios (ϖ ln ϱ/ϖ lnV S ) P and (ϖ ϱ/ϖ lnV S ) P are free parameters arbitrarily adjusted to fit the tomography and geoid data.
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  • 3
    ISSN: 1440-1738
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Abstract  The Yanbian area is located in the eastern part of the Central Asian Orogenic Belt (CAOB) of China and is characterized by widespread Phanerozoic granitic intrusions. It was previously thought that the Yanbian granitoids were mainly emplaced in the Early Paleozoic (so-called ‘Caledonian’ granitoids), extending east–west along the northern margin of the North China craton. However, few of them have been precisely dated; therefore, five typical ‘Caledonian’ granitic intrusions (the Huangniling, Dakai, Mengshan, Gaoling and Bailiping batholiths) were selected for U–Pb zircon isotopic study. New-age data show that emplacement of these granitoids extended from the Late Paleozoic to Late Mesozoic (285–116 Ma). This indicates that no ‘Caledonian’ granitic belt exists along the northern margin of the North China craton. The granitoids can be subdivided into four episodes based on our new data: Early Permian (285 ± 9 Ma), Early Triassic (249–245 Ma), Jurassic (192–168 Ma) and Cretaceous (119–116 Ma). The 285 ± 9 Ma tonalite was most likely related to subduction of the Paleo-Asian Oceanic Plate beneath the North China craton, followed by Triassic (249–245 Ma) syn-collisional monzogranites, representing the collision of the CAOB orogenic collage with the North China craton and final closure of the Paleo-Asian Ocean. The Jurassic granitoids resulted from subduction of the Paleo-Pacific plate and subsequent collision of the Jiamusi–Khanka Massif with the existing continent, assembled in the Triassic. The Early Cretaceous granitoids formed in an extensional setting along the eastern Asian continental margin.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Geophysical prospecting 51 (2003), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Wide-angle multicomponent ocean-bottom cable (OBC) data should further enhance sub-basalt imaging by using both compressional and converted shear wavefields. The first step in analysing multicomponent OBC data is to decompose the recorded wavefields into pure P- and pure S-wavefields, and extract the upgoing P- and S-waves. This paper presents a new scheme to separate P- and S-wavefields from wide-angle multicomponent OBC data in the τ–p domain. By considering plane-wave components with a known horizontal slowness, the P- and S-wavefields are separated into the directions of observed P- and S-wave oscillations using the horizontal and vertical components of the data. The upgoing P- and S-waves are then extracted from the separated P- and S-wavefields. The parameters used in the separation are the seismic wave velocities and the density at the receiver location, which can be estimated from the first reflection phase observed on the horizontal and vertical components. Numerical tests on synthetic data for a plane-layered model show good performance and demonstrate the accuracy of the scheme. Separation of wavefields from a basalt model is performed using synthetic wide-angle multicomponent OBC data. The results show that both near-offset and wide-angle reflections and conversions from within and below basalt layers are enhanced and clearly identified on the separated wavefields.
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  • 5
    Publication Date: 2017-09-20
    Description: 230Th and 231Pa are produced in sea water by radioactive decay of Uranium isotopes (234U, 235U). Both are particle reactive and are scavenged onto settling particles. As 230Th is more particle reactive than 231Pa, their distribution in the water column and activity ratio give information about particle fluxes and circulation patterns and –intensities. Both particle fluxes and deep water circulation may respond to climatic changes in the Arctic Ocean. This study discusses temporal changes in radionuclide concentration in the context of climate change. We compare results from 1991 [1] 2007 and 2015. We present results of dissolved 231Pa and 230Th activities of samples collected in the Nansen-, Amundsenand Makarov Basins during GEOTRACES sections GIPY11 (2007, 4 stations), GN04 (2015, 10 stations) aboard RV Polarstern. Our discussion of factors controlling the 230Th and 231Pa distribution is supported by, dissolved CFC, dissolved iron and particulate 230Th and 231Pa (3 stations) collected during GEOTRACES section GN04. We find that distributions and concentrations of dissolved 231Pa and 230Th in the central Arctic Ocean have changed significantly since 1991. Dissolved 231Pa concentrations in the Makarov basin decreased by half within less than 20 years. These changes are discussed in the context of environmental changes, such as declining sea ice cover and related increase of particle fluxes or changing deep water circulation. [1] Scholten, J. C., et al. (1995). Deep-Sea Research II 42: 1519- 1531
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
    Format: application/pdf
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  • 6
    Publication Date: 2018-03-26
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 7
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Two-layer antireflective films were prepared on Na-Mg-Ca-Si glass substrate by sol-gel process starting from metal alkoxides: Si(OC2H5)4, Ti(OC4H9)4. The transmittance of glass was increased obviously (〉95%), the reflective index was reduced to 1.95 through visible light range. TEM observation showed that SiO2 film is compactly joined to TiO2 film and TiO2 film to the substrate. TEM-EDX analysis of the films, film-substrate interface and substrate revealed that with the increase of Ti content, the content of Mg,Ca and Si decreases, however, the content of Na increases. The diffuse of Na+ from the substrate to the film is negative diffusion
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 2004
    Keywords: CC 1/1 ; Coordinating Committee ; Himalayas
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  • 9
    ISSN: 1745-4581
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A membrane separator/bioreactor system was developed for rapid detection of Escherichia coli O157:H7. The system consisted of a membrane separator/bioreactor (0.45 μm of the pore size) to separate the-complexes of E. coli O157:H7 and alkaline phosphatase-conjugated anti-E. coli O157:H7 antibodies from the sample and to produce p-nitrophenol through the enzymatic reaction (p-nitrophenyl phosphate hydrolysis), and an optical detector for measuring the p-nitrophenol absorbance at 400 nm. The membrane material and the flow rate of the substrate for the enzymatic hydrolysis had great effects on the absorbance of p-nitrophenol. The optimum conditions for the enzymatic reaction were determined as 1.0 M Tris buffer, pH 8.0, and 0.1 M MgCl2 for this system. The detection range was 104± 107 CFU/mL with a relative standard deviation of 4.3 ± 14.2%, and whole procedure could be completed in 50 min without any enrichment and culture. Other bacteria such as Salmonella typhimurium, Campylobacter jejuni and Listeria monocytogenes had no significant interference with the detection of E. coli O157:H7.
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  • 10
    ISSN: 1745-4565
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Electrical stimulation was evaluated as a method to kill Salmonella typhimurium in various salt solutions at different concentration. Salmonella typhimurium at 2 × 105 CFU/ml was treated at 22–24C for 60 min in each salt solution using electricity at 10 mA/cm2 current, 1 kHz frequency, and 50% duty cycle. Samples taken at various times were serially diluted, plated on tryptic soy agar and xylose lysine desoxycholate agar, and incubated at 37C for 18–24 h. To detect injured cells, samples were also pre-enriched in buffered peptone water at 37C for 4–5h before being plated. Results indicated all salmonellae were electrically killed at 5 min in NaCl, at 30 min in NaNO3, and at 45 min in NaC2H3O2 at 0.15 and 0.015 M concentrations. Salmonellae were also killed at 45 min in Na3PO4 and at 60 min in Na2CO3 at 0.0015 M concentration by electricity in combination with high pH.
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