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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 26 (1993), S. 1344-1358 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2136-2138 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Various sample sizes of Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 with masses up to 80 mg were undercooled below Tg (the glass transition temperature) while electrostatically levitated. The final solidification product of the sample was determined by x-ray diffraction to have an amorphous phase. Differential scanning calorimetry was used to confirm the absence of crystallinity in the processes sample. The amorphous phase could be formed only after heating the samples above the melting temperature for extended periods of time in order to break down and dissolve oxides or other contaminants which would otherwise initiate heterogeneous nucleation of crystals. Noncontact pyrometry was used to monitor the sample temperature throughout processing. The critical cooling rate required to avoid crystallization during solidification of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 alloy fell between 0.9 and 1.2 K/s. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 674-687 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure of the magnetic fluctuations in a tokamak has been determined from extensive measurements using a variety of probes outside the limiter in TEXT [Plasma Phys. Controlled Nucl. Fusion 27, 1335 (1985)]. The spectrum has been measured to 500 kHz, but little energy is present above 150 kHz. The spectrum ranges from low-frequency, low-m-number modes with high coherence to higher m values at higher frequencies, which have limited poloidal and temporal coherence but are specifically correlated with electrostatic fluctuations in the edge. Although these magnetic fluctuations are not directly significant for transport, they are a useful indication of edge turbulence. They are associated with turbulence only inside the limiter. The correlation length along field lines is long, and the phase variation of the correlated components suggests k(parallel)/k⊥ (approximately-equal-to) 0.005. These magnetic signals are consistent with a modest modulation of the plasma resistivity in the edge as in resistivity-gradient-driven modes, but the magnetic fluctuation signal is not proportional to the applied E(parallel). Their response to many other perturbations is reported.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 2922-2928 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Several experiments have been devised to measure plasma fluctuations in an effort to help elucidate a possible connection between plasma microturbulence and anomalous transport. Results from microwave scattering on the Tokamak Fusion Test Reactor (TFTR) [Nucl. Fusion 18, 1089 (1978)] show that the level of plasma fluctuations increases toward the long-wavelength region (k⊥ρs≤0.2), at which point the fluctuations cannot be spatially resolved. The desire to measure long-wavelength fluctuations has motivated the development of two fluctuation diagnostics, beam emission spectroscopy (BES), and microwave reflectometry on TFTR. BES measures long-wavelength density fluctuations (k⊥≤2 cm−1) by observing the fluorescence emitted from collisionally excited atoms in a TFTR heating beam. In L-mode discharges with relatively flat density profiles, the fluctuations measured with BES are concentrated in the low-frequency region (≤30 kHz). In the laboratory frame, the fluctuations have a poloidal propagation velocity that is approximately equal to that of the plasma rotation, and the frequency spectra are broadened by Doppler effects. Measured fluctuation levels are 5%–10% at the edge of the plasma. In the core, the level falls to less than 1%, which is comparable to observations made with microwave reflectometry and scattering. The fluctuation level in the core (r/a=0.7) is seen to increase with injected beam power, as is observed with microwave scattering at shorter wavelengths (k⊥≈2–10 cm−1). In contrast, the fluctuation level in the edge region does not change significantly with neutral beam power.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A spectroscopic diagnostic for measurement of slowing-down alpha particles is under development and will be implemented for D–T operation of the Tokamak Fusion Test Reactor. The visible 468.6 nm He+ line (n=3–4) is excited by charge exchange recombination of alphas with a heating neutral beam (55 keV/amu), and the distortion of the line profile caused by alphas with energies up to 0.5–1.0 MeV is observed. Expected intensities are 0.1%–10% of the bremsstrahlung background for D–T discharges with Q=0.2–1.0. Because the signal is small, a high-throughput optical system is needed to achieve the desired signal-to-noise ratio of 10–100. Vertical and horizontal arrays of sightlines with five spatial channels will be used. Initially, two spatial channels will be coupled via fiber optics to an f/3.8 spectrometer equipped with a low-noise charge coupled device detector, with expansion to 5–10 spatial channels planned for D–T operation.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A flexible beam emission spectroscopy diagnostic system is being installed on the Phaedrus-T tokamak. It consists of a low-power diagnostic neutral beam (H0 or He0) coupled with visible and vacuum UV collection optics to study low-amplitude, high-frequency fluctuations in local plasma density in ohmically and rf-heated plasmas. Neutral beam geometry and optical sightlines are chosen to optimize localization and radial resolution (〈1 cm) over the whole plasma region. The ability to inject either a H or He neutral beam and observe in both the vacuum UV and the visible spectral ranges allows a wide choice of atomic transitions (e.g., Hα, Lα, He singlet or triplet lines, etc.) to be compared and optimized for a given experimental condition.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4934-4936 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For the next generation, burning tokamak plasmas such as in the International Thermonuclear Experimental Reactor (ITER), diagnostic neutral beams and beam spectroscopy will continue to be used to determine a variety of plasmas parameters such as ion temperature, rotation, fluctuations, impurity content, current density profile, and confined alpha particle density and energy distribution. Present-day low-current, long-pulse beam technology will be unable to provide the required signal intensities because of higher beam attenuation and background bremsstrahlung radiation in these larger, higher-density plasmas. To address this problem, we are developing a short-pulse, intense diagnostic neutral beam. Protons or deuterons are accelerated using magnetic-insulated ion-diode technology, and neutralized in a transient gas cell. A prototype 50-kA, 100-kV, 1-μs accelerator is under construction at Los Alamos. Initial experiments will focus on ITER-related issues of beam energy distribution, current density, pulse length, divergence, propagation, impurity content, reproducibility, and maintenance.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 676-680 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Solidification of selected Mn-Al-C alloys during containerless levitation and rapid quenching has yielded the first report for a ferromagnetic metastable τ (L10) phase formed directly from the melt. Complete solidification to τ phase was interrupted by the competitive evolution of an equilibrium ε phase during recalescence. The amount of undercooling required to produce the metastable ferromagnetic τ phase in a Mn0.55Al0.433C0.017 alloy during solidification was estimated as approximately 470 K based on differential thermal analysis results. When the alloy carbon content was increased to 3.4 at. % (i.e., Mn0.55Al0.416Co0.034 alloy), a transition in structure development occurred so that the samples exhibited γ2 phase formation as well as τ and ε phases. Both microstructural observations and x-ray diffraction examination were used to guide the interpretation and the analysis of solidification pathways. The attainment of the high liquid undercooling required to nucleate the metastable τ phase from the melt may be facilitated by containerless processing.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 38 (1993), S. 619-623 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The effect of temperature and O2 saturation on the production of recombinant proteins β-galactosidase and human glucocerebrosidase by Spodoptera frugiperda cells (Sf9) infected with recombinant Autographa californica nuclear polyhedrosis virus was investigated. The rates of cell growth, glucose consumption, O2 consumption and product expression were measured at temperatures between 22° C and 35° C. The results indicated that possible O2 limitation may be alleviated without compromising the maximum cell yield by lowering the incubation temperature from 27° C to 25° C. The expression level of the recombinant proteins at 27° C was similar to that obtained at 22° C and 25° C; lower protein yields were obtained at 30° C. An increase in temperature from 22° C to 27° C led to earlier production of the proteins and to an increase in the proportion of the product released outside the cells.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 235-239 
    ISSN: 0006-3592
    Keywords: insect cells ; high density culture ; recombinant protein production ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of the growth phase of Spodoptera frugiperda (Sf9) cells on the production of recombinant proteins (β-galactosidase and glucocerebrosidase) was investigated. Cells infected with the recombinant Autographa californica nuclear polyhedrosis virus at the late exponential and stationary phases yielded low quantities of expressed protein. Highest enzyme yields were obtained using Sf9 cells from the early exponential phase (0.9 mg β-galactosidase/106 cells and 1.7 μg glucocerebrosidase/106 cells). Infection of resuspension of cells collected from various phases of growth in fresh medium resulted in 75% restoration of maximal expression levels. This finding suggested either nutrient limitation or waste product accumulation as the cause of the decrease in productivity at the latter phases of growth. Further experiments revealed that the highest productivity levels could be obtained with cultures of Sf9 cells grown in a fermentor to a cell concentration of 4 × 106 mL-1. The medium needed to be replaced prior to infection with the recombinant virus and supplemented with a mixture of glucose, L-glutamine, and yeastolate ultrafiltrate. © 1993 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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