Refine
Year of publication
- 2024 (2)
- 2023 (7)
- 2022 (12)
- 2021 (8)
- 2020 (9)
- 2019 (12)
- 2018 (16)
- 2017 (12)
- 2016 (26)
- 2015 (22)
- 2014 (24)
- 2013 (26)
- 2012 (14)
- 2011 (22)
- 2010 (14)
- 2009 (15)
- 2008 (9)
- 2007 (14)
- 2006 (12)
- 2005 (10)
- 2004 (8)
- 2003 (7)
- 2002 (13)
- 2001 (12)
- 2000 (8)
- 1999 (11)
- 1998 (19)
- 1997 (13)
- 1996 (7)
- 1995 (19)
- 1994 (18)
- 1993 (5)
- 1992 (17)
- 1991 (5)
- 1990 (9)
- 1989 (12)
- 1988 (13)
- 1987 (8)
- 1986 (5)
- 1985 (6)
- 1984 (6)
- 1983 (4)
- 1982 (3)
- 1981 (1)
- 1980 (2)
- 1979 (1)
- 1978 (2)
- 1973 (1)
- 1971 (1)
Document Type
- Article (454)
- Conference Proceeding (23)
- Part of a Book (18)
- Patent (17)
- Book (9)
- Preprint (1)
Language
- English (522) (remove)
Has Fulltext
- no (522) (remove)
Keywords
- Heparin (3)
- Chemometrics (2)
- IR spectroscopy (2)
- NMR spectroscopy (2)
- Principal component analysis (2)
- Standardization (2)
- (R)- or (S)- gamma-valerolactone (1)
- 4-hydroxy valeric acid (1)
- Alginate beads (1)
- Analytics (1)
- Authenticity (1)
- Bioeconomy (1)
- Bioethanol (1)
- Biomass (1)
- Biorefinery (1)
- Biorefinery definitions (1)
- Bladder (1)
- Bragg peak (1)
- CRISPR/Cas9 (1)
- Chimeric liver-humanized mice (1)
Institute
- Fachbereich Chemie und Biotechnologie (522) (remove)
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.
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.
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.