| 1. |
- Enfors, Sven-Olof, et al.
(författare)
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Physiological responses to mixing in large scale bioreactors
- 2001
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Ingår i: Journal of Biotechnology. - 0168-1656 .- 1873-4863. ; 85:2, s. 175-185
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Tidskriftsartikel (refereegranskat)abstract
- Escherichia coli fed-batch cultivations at 22 m(3) scale were compared to corresponding laboratory scale processes and cultivations using a scale-down reactor furnished with a high-glucose concentration zone to mimic the conditions in a feed zone of the large bioreactor. Formate accumulated in the large reactor, indicating the existence of oxygen limitation zones. It is suggested that the reduced biomass yield at large scale partly is due to repeated production/reassimilation of acetate from overflow metabolism and mixed acid fermentation products due to local moving zones with oxygen limitation. The conditions that generated mixed-acid fermentation in the scale-down reactor also induced a number of stress responses, monitored by analysis of mRNA of selected stress induced genes. The stress responses were relaxed when the cells returned to the substrate limited and oxygen sufficient compartment of the reactor. Corresponding analysis in the large reactor showed that the concentration of mRNA of four stress induced genes was lowest at the sampling port most distant from the feed zone. It is assumed that repeated induction/relaxation of stress responses in a large bioreactor may contribute to altered physiological properties of the cells grown in large-scale bioreactor. Flow cytometric analysis revealed reduced damage with respect to cytoplasmic membrane potential and integrity in cells grown in the dynamic environments of the large scale reactor and the scale-down reactor.
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| 2. |
- Henschel, W, et al.
(författare)
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Electrical characterization of 12 nm EJ-MOSFETs on SOI substrates
- 2004
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Ingår i: Solid-State Electronics. - : Elsevier BV. - 0038-1101 .- 1879-2405. ; 48:5, s. 739-745
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Tidskriftsartikel (refereegranskat)abstract
- A dual gate metal oxide semiconductor field effect transistor (MOSFET) with electrically variable shallow junctions (EJ-MOSFET) has been fabricated on silicon on insulator (SOI) substrates. This kind of transistor allows testing the limits of scalability at relaxed process requirements. Transistor gate lengths down to 12 run have been structured by electron beam lithography (EBL) and specific etching processes. The coupling of the upper gate to the inner transistor is carefully investigated.
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| 3. |
- Henschel, W, et al.
(författare)
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Fabrication of 12 nm electrically variable shallow junction metal-oxide-semiconductor field effect transistors on silicon on insulator substrates
- 2003
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 21:6, s. 2975-2979
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Tidskriftsartikel (refereegranskat)abstract
- Electrically variable shallow junction metal-oxide-semiconductor field effect transistors on silicon on insulator have been fabricated to evaluate the suitability of fabrication processes on a nanoscale. In addition, the limits of scalability have been explored reducing gate lengths down to 12 nm. Specific attention has been paid to the overlay accuracy as required for the fabrication of these double gate structures. The superior quality of hydrogen silsesquioxane (HSQ) as electron beam resist and as mask material is demonstrated. The transistor fabricated exhibits extremely low leakage currents and relatively high on currents. The 8 orders of magnitude difference between the on and off states demonstrates conclusively large potentials for metal-oxide-semiconductor structures with critical dimensions in the 10 nm regime. (C) 2003 American Vacuum Society.
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| 4. |
- Scheffle, M., et al.
(författare)
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Low cost large area panel processing of MCM-D substrates and packages
- 2001
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Ingår i: Proceedings of IPACK’01. ; , s. -8
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Konferensbidrag (refereegranskat)abstract
- The paper describes the results of the EU research project LAP that had the target to develop and to demonstrate a low-cost high-density substrate manufacturing technology for 1st-level die assemblies. The cost target of 1€€/in2 had to be obtained by increasing toady’s 4x4in2 panel sizes to panels upto 24x24in2. The results focus on RF characterization (integrated antennas up to 83GHz, inductors up a Q value of 50), novel packaging strategies (integration of substrate and package), and cost achievements (approaching the cost target). The technology capabilities have been demonstrated with a 9:4 satellite switch operating up to 2.4GHz and readout electronics for physics experiments.
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| 9. |
- Kovacs, T., et al.
(författare)
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Flow and turbulence in the discharge of radial pumping turbines : Influence of the turbine type
- 2001
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Ingår i: Chemical Engineering & Technology. - 0930-7516 .- 1521-4125. ; 24:10, s. 1035-1044
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Tidskriftsartikel (refereegranskat)abstract
- Velocity measurements were made in the impeller discharge of 6SRGT- and Rushton-type impellers in a 0.6 m(3) tank using, constant temperature anemometry with a direction sensitive split-film probe. The reproducibility error of the measurement system was found to be greater than 5 % for all measured properties. The main flow and turbulent parameters measured at three agitation rates in the impeller discharge are compared for the two turbines with respect to both agitation rate and the measured power input. For comparison of the flow properties in the centerline of the two turbines having different diameter and blade height, a uniform representation was used treating the impeller stream as a special kind of free jet. Using this representation, we obtained similar results for both turbines on all measured parameters. The profile measurements showed a similar main flow field for both turbines, but significant differences were found in the axial distribution of turbulent kinetic energy and the energy dissipation rate.
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| 10. |
- Kovacs, T., et al.
(författare)
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Fourier spectrum to recover deterministic and stochastic behavior in stirred tanks
- 2001
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Ingår i: AIChE Journal. - : Wiley. - 0001-1541 .- 1547-5905. ; 47:10, s. 2167-2176
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Tidskriftsartikel (refereegranskat)abstract
- Velocity data from the impeller region of Rushton and 6SRGT pilot-scale impellers were analyzed both in the frequency domain and with respect to periodicity. The four characteristic frequencies and their combination were detected from the Fourier spectrum, and the deterministic part of the signal was recovered by making the amplitude of the other frequencies zero. The deterministic part was then analyzed with tools from nonlinear theories. For the two turbine-types, the dynamics of the deterministic velocity parts were almost identical. The turbulent part of the signal could also be estimated in a similar manner.
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