TY  - JOUR
A1  - Tippkötter, Nils
A1  - Deterding, A.
A1  - Ulber, Roland
T1  - Determination of acetic acid in fermentation broth by gas-diffusion technique
JF  - Engineering in Life Sciences
N2  - Due to the interfering effects of acetic acid in many fermentation processes, a gas-diffusion technique was developed for the online determination of acetic acid. The measurements were accomplished with a flow diffusion analysis (FDA) unit from the TRACE Analytics GmbH, Braunschweig, Germany. The diffusion analysis is based on the UV-absorbance of acetic acid at 205 nm. The measurement was achieved by the separation of an acceptor and a carrier stream (acidified fermentation broth) using a gas permeable polytetrafluoroethylene (PTFE) membrane, whereby broth constituents that would otherwise disturb the UV-measurement of acetic acid, are held back efficiently. Merely, the fermentation by-products, e.g. formic acid, is capable of diffusing through the membrane. While formic acid can disturb the measurement, carbon dioxide does not absorb at 205 nm. The method operates with time-dependent sample enrichment. During the analysis, a small volume of the acceptor stream is stopped for a defined time interval in the acceptor chamber. During this period, the gaseous acetic acid diffuses through the membrane and is enriched in the acceptor chamber. Subsequently after the enrichment, the acceptor stream flows through a UV-detector. The intensity of the signal is proportional to the acetic acid concentration. Online measurements in bioreactors via a sterile filtration probe have been accomplished. A linear calibration in the range of 0.5–5.0 g/L acetic acid with a relative standard deviation of <5 % was obtained. A sampling rate of 8 samples per hour was possible. The system was applied for the determination of acetic acid in E. coli fermentation broth. The instrument is easy to clean, very user-friendly and does not require any toxic or expensive reagents.
Y1  - 2008
U6  - http://dx.doi.org/10.1002/elsc.200820227
VL  - 8
IS  - 1, Special Issue: Technical Systems for the Use in Life Sciences
SP  - 62
EP  - 67
ER  - 
TY  - JOUR
A1  - Lerchl, Alexander
A1  - Krüger, Heike
A1  - Niehaus, Michael
A1  - Streckert, Joachim R.
A1  - Bitz, Andreas
A1  - Hansen, Volkert
T1  - Effects of mobile phone electromagnetic fields at nonthermal SAR values on melatonin and body weight of Djungarian hamsters (Phodopus sungorus)
JF  - Journal of Pineal Research
Y1  - 2008
U6  - http://dx.doi.org/10.1111/j.1600-079X.2007.00522.x
SN  - 1600-079X
VL  - 44
IS  - 3
SP  - 267
EP  - 272
ER  - 
TY  - JOUR
A1  - Albracht, Kirsten
A1  - Arampatzis, A.
A1  - Baltzopoulos, V.
T1  - Assessment of muscle volume and physiological cross-sectional area of the human triceps surae muscle in vivo
JF  - Journal of Biomechanics
Y1  - 2008
U6  - http://dx.doi.org/10.1016/j.jbiomech.2008.04.020
SN  - 0021-9290
VL  - 41
SP  - 2211
EP  - 2218
ER  - 
TY  - JOUR
A1  - Fleischhaker, Robert
A1  - Evers, Jörg
T1  - Four-wave mixing enhanced white-light cavity
JF  - Physical Review A - Atomic, molecular, and optical physics
Y1  - 2008
SN  - 0556-2791
VL  - 78
IS  - 5
SP  - 051802(R)
ER  - 
TY  - JOUR
A1  - Fleischhaker, Robert
A1  - Evers, Jörg
T1  - Nonlinear effects in pulse propagation through Doppler-broadened closed-loop atomic media
JF  - Physical Review A - Atomic, molecular, and optical physics
Y1  - 2008
U6  - http://dx.doi.org/10.1103/PhysRevA.77.043805
SN  - 1050-2947
VL  - 77
IS  - 4
SP  - 043805
ER  - 
TY  - JOUR
A1  - Mahmoudi, Mohammad
A1  - Fleischhaker, Robert
A1  - Sahrai, Mostafa
A1  - Evers, Jörg
T1  - Group velocity control in the ultraviolet domain via interacting dark-state resonances
JF  - Journal of physics B: Atomic, molecular and optical physics
Y1  - 2008
U6  - http://dx.doi.org/10.1088/0953-4075/41/2/025504
SN  - 0953-4075
SN  - 1361-6455
VL  - 41
IS  - 2
SP  - 25504
EP  - 25600
ER  - 
TY  - JOUR
A1  - Butenweg, Christoph
A1  - Gellert, Christoph
A1  - Kranzler, Thomas
T1  - Pseudo-dynamische Versuche an Reihenmittelhäusern – Vergleich mit aktuellen Berechnungsansätzen
JF  - Mauerwerk : European journal of masonry
Y1  - 2008
U6  - http://dx.doi.org/10.1002/dama.200800397
SN  - 1437-1022 (E-Journal); 1432-3427 (Print)
VL  - Volume 12
IS  - Issue 6
SP  - 315
EP  - 326
ER  - 
TY  - JOUR
A1  - Mottaghy, Darius
A1  - Vosteen, Hans-Dieter
A1  - Schellschmidt, Rüdiger
T1  - Temperature dependence of the relationship of thermal diffusivity versus thermal conductivity for crystalline rocks
JF  - International Journal of Earth Sciences
Y1  - 2008
U6  - http://dx.doi.org/10.1007/s00531-007-0238-3
SN  - 1437-3262
VL  - 97
IS  - 2
SP  - 435
EP  - 442
ER  - 
TY  - JOUR
A1  - Baier, C.
A1  - Mottaghy, Darius
A1  - Ziegler, M.
A1  - Rath, V.
T1  - Numerische Simulation des Gefrierprozesses  bei der Baugrundvereisung im durchströmten Untergrund
JF  - Bauingenieur
Y1  - 2008
SN  - 0005-6650
VL  - 83
IS  - 2
SP  - 49
EP  - 60
ER  - 
TY  - JOUR
A1  - Kirsch, Ansgar
T1  - Experimentelle Untersuchung des Ortsbrustversagens seichter Tunnel
JF  - Österreichische Bauwirtschaft
Y1  - 2008
IS  - Sondernr.
SP  - 6
EP  - 9
ER  -