| 1. |
- Rensmo, Håkan, et al.
(författare)
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High light-to-energy conversion efficiencies for solar cells based on nanostructured ZnO electrodes
- 1997
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Ingår i: Journal of Physical Chemistry B. - : AMER CHEMICAL SOC. - 1520-6106 .- 1520-5207. ; 101:14, s. 2598-2601
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Photoelectrochemical properties of nanostructured ZnO thin film electrodes have been investigated in the UV and visible regions. For films consisting of 15 nm large undoped crystallites a maximum monochromatic current conversion efficiency of 58% was obtained in the visible using a ruthenium-based dye as a sensitizer. The overall solar energy conversion efficiency for this film was 2%. In comparison, sensitized films consisting of 150 nm large Al-doped crystallites yield a monochromatic current conversion efficiency of 31% and an overall solar energy conversion efficiency of 0.5%. The study also shows that nanostructured ZnO may give high efficiencies in the UV region, approaching unity for the Al-doped films.
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| 2. |
- Scheffel, Julia, et al.
(författare)
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Design of an integrated continuous downstream process for acid-sensitive monoclonal antibodies based on a calcium-dependent Protein A ligand
- 2022
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1664, s. 462806-462806
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Tidskriftsartikel (refereegranskat)abstract
- Monoclonal antibodies (mAb) are used as therapeutics and for diagnostics of a variety of diseases, and novel antibodies are continuously being developed to find treatments for new diseases. Therefore, the manufacturing process must accommodate a range of mAb characteristics. Acid-sensitive mAbs can severely compromise product purity and yield in the purification process due to the potential formation of aggregates. To address this problem, we have developed an integrated downstream process for the purification of pH-sensitive mAbs at mild conditions. A calcium-dependent Protein A-based ligand, called ZCa, was used in the capture step in a 3-column periodic counter-current chromatography operation. The binding of ZCa to antibodies is regulated by calcium, meaning that acidic conditions are not needed to break the interaction and elute the antibodies. Further, the virus inactivation was achieved by a solvent/detergent method, where the pH could remain unchanged. The polishing steps included a cation and an anion exchange chromatography step, and screening of the capture and polishing steps was performed to allow for a seamless integration of the process steps. The process was implemented at laboratory scale for 9 days obtaining a high yield, and a consistently pure drug substance, including high reduction values of the host cell protein and DNA concentrations, as well as aggregate levels below the detection limit, which is attributed to the mild conditions used in the process.
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| 3. |
- Schwarz, Hubert, et al.
(författare)
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Integrated continuous biomanufacturing on pilot scale for acid-sensitive monoclonal antibodies
- 2022
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 0006-3592 .- 1097-0290.
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we demonstrated the first, to our knowledge, integrated continuous bioprocess (ICB) designed for the production of acid-sensitive monoclonal antibodies, prone to aggregate at low pH, on pilot scale. A high cell density perfusion culture, stably maintained at 100 × 106 cells/ml, was integrated with the downstream process, consisting of a capture step with the recently developed Protein A ligand, ZCa; a solvent/detergent-based virus inactivation; and two ion-exchange chromatography steps. The use of a mild pH in the downstream process makes this ICB suitable for the purification of acid-sensitive monoclonal antibodies. Integration and automation of the downstream process were achieved using the Orbit software, and the same equipment and control system were used in initial small-scale trials and the pilot-scale downstream process. High recovery yields of around 90% and a productivity close to 1 g purified antibody/L/day were achieved, with a stable glycosylation pattern and efficient removal of impurities, such as host cell proteins and DNA. Finally, negligible levels of antibody aggregates were detected owing to the mild conditions used throughout the process. The present work paves the way for future industrial-scale integrated continuous biomanufacturing of all types of antibodies, regardless of acid stability.
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| 4. |
- Solbrand, Anita
(författare)
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Charge transport in nanostructured metal oxide thin film electrodes
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nanostructured metal oxide electrodes are of great interest due to its wide field of potential applications, e.g. solar cells and batteries. The electron transport in nano-structured TiO2 and ZnO thin film electrodes was studied with time-resolved photo-currents and steady-state measurements. The results were discussed using a diffusion model for the electron transport and relations for the photocurrent transients were deduced, The experimental results were fitted to simulations giving diffusion coefficients for the electron transport of 1.5·10-5 cm2/s for TiO2 in 0.7 M LiClO4, 0.6·10-5 cm2/s for dye-sensitized TiO2 in 0.1 M KI and 1·10-4 cm2/s to 1·10-6 cm2/s, depending on potential for ZnO in 0.5 M LiC1O4.The electron transport was found to be dependent on potential, light intensity and electrolyte composition, both in time-resolved and steady-state measurements. The potential dependence was more pronounced for ZnO. Electron scavenging species in the electrolyte such as O2 was found to increase the electron losses and surface treatments with e.g. pyridine was found to decrease electron losses. The electron losses were larger for TiO2 than for ZnO.The intercalation of Li+ ions in TiO2 was studied with chronoamperometry and cyclic voltammerty. The entire area was found to be active in the intercalation process and the chemical diffusion coefficients for the insertion and extraction of Li+ were determined to 1·10-17 cm2/s and 4·10-17 cm2/s, respectively. Kinetic information about the processes was also obtained.
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| 5. |
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