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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 4555-4568 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A predictive formalism is developed that is applicable to the large class of activated physical systems described by a differential equation of the generic form: ∂n(φ,t)/∂t =−n(φ,t)F(t) exp(−(φ−R(t))/A(t)). Practical techniques to predict the behavior of activated physical systems for arbitrary time-dependent environments are both intuitively and mathematically developed. Useful techniques to experimentally determine the initial distribution of activation energies, utilizing arbitrary time-dependent laboratory environments, are presented. A number of fundamental results regarding the correct use and interpretation of common diagnostic techniques, such as Arrhenius plots, are derived. It is shown how the predictive results significantly enhance the ability to quantitatively evaluate the reliability of physical systems whose rate-limiting mechanisms are activated processes obeying the above differential equation. Specific issues regarding integrated circuit reliability are examined as potential applications of this predictive formalism, including time-dependent dielectric breakdown, metal electromigration, nonvolatile memory retention, annealing of radiation-induced trapped charge, and thin ferroelectric film switching properties.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2617-2628 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The properties of physical systems whose observable properties depend upon random exceedances of critical parameters are quantitatively examined. Using extreme value theory, the dynamical behavior of this broad class of systems is derived. This class of systems can exhibit two characteristic signatures: generalized activation when far from equilibrium and noise with a characteristic power spectrum (including 1/f ) when in quasiequilibrium. Fractal structures can also arise from these systems. It is thus demonstrated that generalized activation, noise, and fractals, in some cases, are simply different manifestations of a single common dynamical principle, which is termed "extremal dynamics.'' Examples of physical processes governed by extremal dynamics are discussed, including data loss of nonvolatile memories and dielectric breakdown.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 5 (1966), S. 193-198 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry 53 (1961), S. 127-130 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 47 (1982), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Electrical energy consumption and oil recovery were measured during operation of a commercial citrus peel oil centrifugation process. Two parts of a centrifuge's electrical consumption were identified: regular operation and the discharge cycle. During discharge cycles, the electrical energy ranged from 125–189% of the steady-state values. Energy costs were computed for the desludger and polisher centrifuges. Direct electrical costs for the oil mill totaled 0.67/kg oil recovered. Electrical costs calculated for finishing and dewaxing totaled 0.5/kg oil. Actual oil yield (1.1 kg/t) was only 20% of the total in the fruit. A major source of oil loss occurred during extraction from the fruit, where less than 50% of the oil was actually extracted into the dilute emulsion. Inefficient operation of the centrifuges accounted for most of the remaining losses.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Bioprocess and biosystems engineering 3 (1988), S. 113-122 
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Ammonia and lactate are the major byproducts from mammalian cells grown in medium containing glutamine and glucose. Both can be toxic to cells, and may limit the productivity of commercial bioreactors. The transient and steady-state responses of hybridoma growth and metabolism to lactate and ammonia pulse and step changes in continuous suspension culture have been examined. No inhibition was observed at 40 mM lactate. Cell growth was inhibited by 5 mM ammonia, but the cells were able to adapt to ammonia concentrations as high as 8.2 mM. Ammonia production decreased and alanine production increased in response to higher ammonia concentrations. Increased ammonia concentrations also inhibited glutamine and oxygen consumption. The specific oxygen consumption rate decreased by an order of magnitude after an ammonia pulse to 18 mM. Under these conditions, over 90% of the estimated ATP production was due to glycolysis and a large fraction of glutamine was converted to lactate.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Bioprocess and biosystems engineering 3 (1988), S. 103-111 
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Oxygen is an important nutrient that may limit the productivity of commercial cell culture reactors. The transient responses of hybridoma growth and metabolism to step changes in the oxygen supply rate have been examined for dissolved oxygen concentrations (DO) ranging from 0.1% to 10% of air saturation in continuous culture. Metabolic quotients are reported for glucose, lactate, ammonia, oxygen, glutamine, alanine and other amino acids. A majority of the estimated ATP production was due to oxidative phosphorylation under all conditions tested. Decreases in the oxygen supply rate below the value required to maintain 0.5% DO caused the viable cell concentration to decrease. Glycolysis was enhanced at the lower oxygen concentrations, and after an initial decrease, the specific glutamine consumption rate was also higher. High residual glutamine concentrations occurred below 0.5% DO. Oxidation of other amino acids and production of serine were also inhibited. The cells subsequently adapted to low oxygen concentrations. The increase in cell concentration following the return to 10% DO was preceded by increased biosynthetic activity, as evidenced by transiently reduced yields of lactate from glucose, and alanine and ammonia from glutamine.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-0778
    Keywords: bone marrow rescue therapy ; ex vivo expansion ; in vivo model ; neutropenia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In this paper, we develop a simple four parameter population balance model of in vivo neutrophil formation following bone marrow rescue therapy. The model is used to predict the number and type of neutrophil progenitors required to abrogate the period of severe neutropenia that normally follows a bone marrow transplant. The estimated total number of 5 billion neutrophil progenitors is consistent with the value extrapolated from a human trial. The model provides a basis for designing ex vivo expansion protocols.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 59 (1985), S. 509-516 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The magnetic susceptibilities of SnMo6S8, PbMo6.35S8, and PbMo6.2S8 have been measured. There appear to be transitions at about 40 and 100 K. The behavior of the susceptibility is believed to be caused by changes in the lattice, affecting the charge transfer from the tin or lead atoms to the Mo6S8 clusters.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 693-700 
    ISSN: 0006-3592
    Keywords: glucose ; lactate ; real-time determination ; hematopoietic cell culture ; colony-forming cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Glucose and lactate metabolic rates were evaluated for cultures of cord blood (CB) mononuclear cell (MNC), peripheral blood (PB) MNC, and PB CD34+ cell cultures carried out in spinner flasks and in T-flasks in both serum-containing and serum-free media. Specific glucose uptake rates (qgluc, in micromoles per cell per hour) and lactate generation rates (qlac) correlated with the percentage of colony-forming cells (CFC) present in the culture for a broad range of culture conditions. Specifically, the time of maximum CFC percentage in each culture coincided with the time of maximum qgluc and qlac in cultures with different seeding densities and cytokine combinations. A two-population model (Qlac = α[CFC] + β([TC] - [CFC]), where [TC] is total cell concentration; Qlac is volumetric lactate production rate in micromoles per milliliter per hour; α is qlac for an average CFC; and β is qlac for an average non-CFC) was developed to describe lactate production. The model described lactate production well for cultures carried out in both T-flasks and spinner flasks and inoculated with either PB or CB MNC or PB CD34+ cells. The values for α and β that were derived from the model varied with both the inoculum density and the cytokine combination. However, preliminary results indicate that cultures carried out under the same conditions from different samples with similar initial CD34+ cell content have similar values for β and β. These findings suggest that it should be possible to use lactate production data to predict the harvest time that corresponds to the maximum number of CFC in culture. The ability to harvest ex vivo hematopoietic cultures for transplantation when CFC are at a maximum has the potential to speed the rate at which immunocompromised patients recover. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 693-700, 1997.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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