TY - JOUR A1 - Tippkötter, Nils A1 - Roikaew, W. A1 - Ulber, Roland T1 - Nitrate removal from whey concentrate with biotechnological regeneration of the waste water JF - European dairy magazine : EDM Y1 - 2008 SN - 0936-6318 IS - 1 SP - 30 EP - 32 ER - TY - JOUR A1 - Elbers, Gereon A1 - Gäb, Martina A1 - Hoffmann, Katharina A1 - Lobe, Melanie T1 - NIR-spectroscopic investigation of foliage of ozone-stressed Fagus sylvatica trees / Gäb, Martina ; Hoffmann, Katharina ; Lobe, Melanie ; Metzger, Rut ; Ooyen, Sven van ; Elbers, Gereon ; Köllner, Barbara JF - Journal of Forest Research. 11 (2006), H. 2 Y1 - 2006 SN - 1341-6979 SP - 69 EP - 75 ER - TY - JOUR A1 - Thiel, Alexander A1 - Tippkötter, Nils A1 - Suck, Kirstin A1 - Sohling, Ulrich A1 - Ruf, Friedrich A1 - Ulber, Roland T1 - New zeolite adsorbents for downstream processing of polyphenols from renewable resources JF - Engineering in Life Sciences N2 - Commercial materials with polyvinylpolypyrrolidone and polymeric amberlites (XAD7HP, XAD16) are commonly used for the adsorptive downstream processing of polyphenols from renewable resources. In this study, beta-zeolite-based adsorbent systems were examined, and their properties were compared to organic resins. Batch adsorption experiments were conducted with synthetic solutions of major polyphenols. Adsorption isotherms and desorption characteristics of individual adsorbent were determined based on these results. Maximum adsorption capacities were calculated using the Langmuir model. For example, the zeolites had capacities up to 203.2 mg/g for ferulic acid. To extend these results to a complex system, additional experiments were performed on rapeseed meal and wheat seed extracts as representative renewable resources. HPLC analysis showed that with 7.5% w/v, which is regarded as the optimum amount of zeolites, zeolites A and B could bind 100% of the major polyphenols as well as release polyphenols at high yields. Additionally, regeneration experiments were performed with isopropyl alcohol at 99°C to evaluate how zeolites regenerate under mild conditions. The results showed only a negligible loss of adsorption capacity and no loss of desorption capacity. In summary, it was concluded that beta-zeolites were promising adsorbents for developing new processes to isolate polyphenols from renewable resources. Y1 - 2013 U6 - https://doi.org/10.1002/elsc.201200188 VL - 13 IS - 3 SP - 239 EP - 246 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Scherer, Ulrich W. A1 - Kratz, J. V. A1 - Gober, M. K. A1 - Zimmermann, H. P. T1 - New nuclide 263 105 / J.V. Kratz, M.K. Gober, H.P. Zimmermann, M. Schädel, W. Brüchle, E. Schimpf, K.E. Gregorich, A. Türler, N.J. Hannink, K.R. Czerwinski, B. Kadkhodayan, D.M. Lee, M.J. Nurmia, D.C. Hoffman, H. Gäggeler, D. Jost, U.W. Scherer, A. Weber JF - Physical Review C . 45 (1992) Y1 - 1992 SP - 1064 EP - 1069 ER - TY - JOUR A1 - Oehlenschläger, Katharina A1 - Volkmar, Marianne A1 - Stiefelmaier, Judith A1 - Langsdorf, Alexander A1 - Holtmann, Dirk A1 - Tippkötter, Nils A1 - Ulber, Roland T1 - New insights into the influence of pre-culture on robust solvent production of C. acetobutylicum JF - Applied Microbiology and Biotechnology N2 - Clostridia are known for their solvent production, especially the production of butanol. Concerning the projected depletion of fossil fuels, this is of great interest. The cultivation of clostridia is known to be challenging, and it is difficult to achieve reproducible results and robust processes. However, existing publications usually concentrate on the cultivation conditions of the main culture. In this paper, the influence of cryo-conservation and pre-culture on growth and solvent production in the resulting main cultivation are examined. A protocol was developed that leads to reproducible cultivations of Clostridium acetobutylicum. Detailed investigation of the cell conservation in cryo-cultures ensured reliable cell growth in the pre-culture. Moreover, a reason for the acid crash in the main culture was found, based on the cultivation conditions of the pre-culture. The critical parameter to avoid the acid crash and accomplish the shift to the solventogenesis of clostridia is the metabolic phase in which the cells of the pre-culture were at the time of inoculation of the main culture; this depends on the cultivation time of the pre-culture. Using cells from the exponential growth phase to inoculate the main culture leads to an acid crash. To achieve the solventogenic phase with butanol production, the inoculum should consist of older cells which are in the stationary growth phase. Considering these parameters, which affect the entire cultivation process, reproducible results and reliable solvent production are ensured. KW - Pre-culture KW - Metabolic shift KW - Acid crash KW - C. acetobutylicum KW - ABE KW - Butanol Y1 - 2024 U6 - https://doi.org/10.1007/s00253-023-12981-8 SN - 1432-0614 VL - 108 PB - Springer CY - Berlin, Heidelberg ER - TY - JOUR A1 - Selmer, Thorsten A1 - Pierik, Antonio J. A1 - Heider, Johann T1 - New glycyl radical enzymes catalysing key metabolic steps in anaerobic bacteria JF - Biological Chemistry. 386 (2005), H. 10 Y1 - 2005 SN - 1431-6730 SP - 981 EP - 988 ER - TY - GEN A1 - Roth, J. A1 - Tippkötter, Nils T1 - New Approach for Enzymatic Hydrolysis of Lignocellulose with Selective Diffusion Separation of the Monosaccharide Products T2 - Chemie Ingenieur Technik N2 - Enzymatic hydrolysis of lignocellulosic material plays an important role in the classical biorefinery approach. Apart from the pretreatment of the raw material, hydrolysis is the basis for the conversion of the cellulose and hemicellulose fraction into fermentable sugars. After hydrolysis, usually a solid-liquid separation takes place, in order to separate the residual plant material from the sugar-rich fraction, which can be subsequently used in a fermentation step. In order to factor out the separation step, the usage of in alginate immobilized crude cellulose fiber beads (CFBs) were evaluated. Pretreated cellulose fibers are incorporated in an alginate matrix together with the relevant enzymes. In doing so, sugars diffuse trough the alginate matrix, allowing a simplified delivery into the surrounding fluid. This again reduces product inhibition of the glucose on the enzyme catalysts. By means of standardized bead production the hydrolysis in lab scale was possible. First results show that liberation of glucose and xylose is possible, allowing a maximum total sugar yield of 75 %. Y1 - 2016 U6 - https://doi.org/10.1002/cite.201650301 SN - 0009-286X SN - 1522-2640 (eISSN) N1 - ProcessNet-Jahrestagung 2016 und 32. DECHEMA-Jahrestagung der Biotechnologen 2016, 12. - 15. September 2016, Eurogress Aachen VL - 88 IS - 9 SP - 1237 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Druckenmüller, Katharina A1 - Günther, Klaus A1 - Elbers, Gereon T1 - Near-infrared spectroscopy (NIRS) as a tool to monitor exhaust air from poultry operations JF - Science of the Total Environment N2 - Intensive poultry operation systems emit a considerable volume of inorganic and organic matter in the surrounding environment. Monitoring cleaning properties of exhaust air cleaning systems and to detect small but significant changes in emission characteristics during a fattening cycle is important for both emission and fattening process control. In the present study, we evaluated the potential of near-infrared spectroscopy (NIRS) combined with chemometric techniques as a monitoring tool of exhaust air from poultry operation systems. To generate a high-quality data set for evaluation, the exhaust air of two poultry houses was sampled by applying state-of-the-art filter sampling protocols. The two stables were identical except for one crucial difference, the presence or absence of an exhaust air cleaning system. In total, twenty-one exhaust air samples were collected at the two sites to monitor spectral differences caused by the cleaning device, and to follow changes in exhaust air characteristics during a fattening period. The total dust load was analyzed by gravimetric determination and included as a response variable in multivariate data analysis. The filter samples were directly measured with NIR spectroscopy. Principal component analysis (PCA), linear discriminant analysis (LDA), and factor analysis (FA) were effective in classifying the NIR exhaust air spectra according to fattening day and origin. The results indicate that the dust load and the composition of exhaust air (inorganic or organic matter) substantially influence the NIR spectral patterns. In conclusion, NIR spectroscopy as a tool is a promising and very rapid way to detect differences between exhaust air samples based on still not clearly defined circumstances triggered during a fattening period and the availability of an exhaust air cleaning system. Y1 - 2018 U6 - https://doi.org/10.1016/j.scitotenv.2018.02.072 SN - 0048-9697 VL - 630 SP - 536 EP - 543 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Svaneborg, Carsten A1 - Karimi-Varzaneh, Hossein Ali A1 - Hojdis, Nils A1 - Fleck, Franz A1 - Everaers, Ralf T1 - Multiscale approach to equilibrating model polymer melts JF - Physical Review E N2 - We present an effective and simple multiscale method for equilibrating Kremer Grest model polymer melts of varying stiffness. In our approach, we progressively equilibrate the melt structure above the tube scale, inside the tube and finally at the monomeric scale. We make use of models designed to be computationally effective at each scale. Density fluctuations in the melt structure above the tube scale are minimized through a Monte Carlo simulated annealing of a lattice polymer model. Subsequently the melt structure below the tube scale is equilibrated via the Rouse dynamics of a force-capped Kremer-Grest model that allows chains to partially interpenetrate. Finally the Kremer-Grest force field is introduced to freeze the topological state and enforce correct monomer packing. We generate 15 melts of 500 chains of 10.000 beads for varying chain stiffness as well as a number of melts with 1.000 chains of 15.000 monomers. To validate the equilibration process we study the time evolution of bulk, collective, and single-chain observables at the monomeric, mesoscopic, and macroscopic length scales. Extension of the present method to longer, branched, or polydisperse chains, and/or larger system sizes is straightforward. Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevE.94.032502 SN - 2470-0053 VL - 94 IS - 032502 PB - AIP Publishing CY - Melville, NY ER - TY - JOUR A1 - Prielmeier, Franz A1 - Lang, E. W. T1 - Multinuclear Spin-Lattice Relaxation Time Studies of Supercooled Aqueous LiCl-Solutions / E .W. Lang, F. X. Prielmeier JF - Berichte der Bunsen-Gesellschaft für Physikalische Chemie. 92 (1988) Y1 - 1988 SN - 0005-9021 SP - 717 ER -