77 research outputs found

    Electron-impact Excitation Of The Lowest Four Excited States Of Argon

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    First-order many-body theory has been used to calculate the differential and integral cross sections for electron-impact excitation of the argon atom to the 4 P03, 4 P23, 4 P13, and 4 P11 electronic states, for incident electron energies of 16, 20, 30, 50, and 80.4 eV. The resulting cross sections are in good agreement with recent results extracted from electron energy-loss measurements on argon. Detailed calculations show that spin-orbit coupling must be included in the P13 wave function in order to describe the electron-impact excitation of the state properly. © 1981 The American Physical Society.2352194221

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    Directed evolution of biomass intensive CHO cells by adaptation to sub-physiological temperature

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    We report a simple and effective means to increase the biosynthetic capacity of host CHO cells. Lonza proprietary CHOK1SV® cells were evolved by serial sub-culture for over 150 generations at 32 °C. During this period the specific proliferation rate of hypothermic cells gradually recovered to become comparable to that of cells routinely maintained at 37 °C. Cold-adapted cell populations exhibited (1) a significantly increased volume and biomass content (exemplified by total RNA and protein), (2) increased mitochondrial function, (3) an increased antioxidant capacity, (4) altered central metabolism, (5) increased transient and stable productivity of a model IgG4 monoclonal antibody and Fc-fusion protein, and (6) unaffected recombinant protein N-glycan processing. This phenotypic transformation was associated with significant genome-scale changes in both karyotype and the relative abundance of thousands of cellular mRNAs across numerous functional groups. Taken together, these observations provide evidence of coordinated cellular adaptations to sub-physiological temperature. These data reveal the extreme genomic/functional plasticity of CHO cells, and that directed evolution is a viable genome-scale cell engineering strategy that can be exploited to create host cells with an increased cellular capacity for recombinant protein production
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