@article{SchwabHojdisLacayoetal.2016,
  author    = {Schwab, Lukas and Hojdis, Nils and Lacayo, Jorge and Wilhelm, Manfred},
  title     = {Fourier-Transform Rheology of Unvulcanized, Carbon Black Filled Styrene Butadiene Rubber},
  series = {Macromolecular Materials and Engineering},
  volume    = {301},
  journal   = {Macromolecular Materials and Engineering},
  number    = {4},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1439-2054},
  doi       = {10.1002/mame.201500356},
  pages     = {457 -- 468},
  year      = {2016},
  abstract  = {Rubber materials filled with reinforcing fillers display nonlinear rheological behavior at small strain amplitudes below γ0 < 0.1. Nevertheless, rheological data are analyzed mostly in terms of linear parameters, such as shear moduli (G′, G″), which loose their physical meaning in the nonlinear regime. In this work styrene butadiene rubber filled with carbon black (CB) under large amplitude oscillatory shear (LAOS) is analyzed in terms of the nonlinear parameter I3/1. Three different CB grades are used and the filler load is varied between 0 and 70 phr. It is found that I3/1(φ) is most sensitive to changes of the total accessible filler surface area at low strain amplitudes (γ0 = 0.32). The addition of up to 70 phr CB leads to an increase of I3/1(φ) by a factor of more than ten. The influence of the measurement temperature on I3/1 is pronounced for CB levels above the percolation threshold.},
  language  = {en}
}
@article{HarishWriggersJungketal.2016,
  author    = {Harish, Ajay B. and Wriggers, Peter and Jungk, Juliane and Hojdis, Nils and Recker, Carla},
  title     = {Mesoscale Constitutive Modeling of Non-Crystallizing Filled Elastomers},
  series = {Computational Mechanics},
  volume    = {57},
  journal   = {Computational Mechanics},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1432-0924},
  doi       = {10.1007/s00466-015-1251-1},
  pages     = {653 -- 677},
  year      = {2016},
  abstract  = {Elastomers are exceptional materials owing to their ability to undergo large deformations before failure. However, due to their very low stiffness, they are not always suitable for industrial applications. Addition of filler particles provides reinforcing effects and thus enhances the material properties that render them more versatile for applications like tyres etc. However, deformation behavior of filled polymers is accompanied by several nonlinear effects like Mullins and Payne effect. To this day, the physical and chemical changes resulting in such nonlinear effect remain an active area of research. In this work, we develop a heterogeneous (or multiphase) constitutive model at the mesoscale explicitly considering filler particle aggregates, elastomeric matrix and their mechanical interaction through an approximate interface layer. The developed constitutive model is used to demonstrate cluster breakage, also, as one of the possible sources for Mullins effect observed in non-crystallizing filled elastomers.},
  language  = {en}
}
@article{HentschkeHagerHojdis2014,
  author    = {Hentschke, Reinhard and Hager, Jonathan and Hojdis, Nils},
  title     = {Molecular Modeling Approach to the Prediction of Mechanical Properties of Silica-Reinforced Rubbers},
  series = {Journal of Applied Polymer Science},
  volume    = {131},
  journal   = {Journal of Applied Polymer Science},
  number    = {18},
  publisher = {Wiley},
  address   = {New York, NY},
  issn      = {1097-4628},
  doi       = {10.1002/app.40806},
  pages     = {1 -- 9},
  year      = {2014},
  abstract  = {Recently, we have suggested a nanomechanical model for dissipative loss in filled elastomer networks in the context of the Payne effect. The mechanism is based on a total interfiller particle force exhibiting an intermittent loop, due to the combination of short-range repulsion and dispersion forces with a long-range elastic attraction. The sum of these forces leads, under external strain, to a spontaneous instability of "bonds" between the aggregates in a filler network and attendant energy dissipation. Here, we use molecular dynamics simulations to obtain chemically realistic forces between surface modified silica particles. The latter are combined with the above model to estimate the loss modulus and the low strain storage modulus in elastomers containing the aforementioned filler-compatibilizer systems. The model is compared to experimental dynamic moduli of silica filled rubbers. We find good agreement between the model predictions and the experiments as function of the compatibilizer's molecular structure and its bulk concentration.},
  language  = {en}
}
@article{EveraersKarimiVarzanehFlecketal.2020,
  author    = {Everaers, Ralf and Karimi-Varzaneh, Hossein Ali and Fleck, Franz and Hojdis, Nils and Svaneborg, Carsten},
  title     = {Kremer-Grest Models for Commodity Polymer Melts: Linking Theory, Experiment, and Simulation at the Kuhn Scale},
  series = {Macromolecules},
  volume    = {53},
  journal   = {Macromolecules},
  number    = {6},
  publisher = {ACS Publications},
  address   = {Washington, DC},
  issn      = {1520-5835},
  doi       = {10.1021/acs.macromol.9b02428},
  pages     = {1901 -- 1916},
  year      = {2020},
  abstract  = {The Kremer-Grest (KG) polymer model is a standard model for studying generic polymer properties in molecular dynamics simulations. It owes its popularity to its simplicity and computational efficiency, rather than its ability to represent specific polymers species and conditions. Here we show that by tuning the chain stiffness it is possible to adapt the KG model to model melts of real polymers. In particular, we provide mapping relations from KG to SI units for a wide range of commodity polymers. The connection between the experimental and the KG melts is made at the Kuhn scale, i.e., at the crossover from the chemistry-specific small scale to the universal large scale behavior. We expect Kuhn scale-mapped KG models to faithfully represent universal properties dominated by the large scale conformational statistics and dynamics of flexible polymers. In particular, we observe very good agreement between entanglement moduli of our KG models and the experimental moduli of the target polymers.},
  language  = {en}
}
@article{MeyerHentschkeHageretal.2017,
  author    = {Meyer, Jan and Hentschke, Reinhard and Hager, Jonathan and Hojdis, Nils and Karimi-Varzaneh, Hossein Ali},
  title     = {Molecular Simulation of Viscous Dissipation due to Cyclic Deformation of a Silica-Silica Contact in Filled Rubber},
  series = {Macromolecules},
  volume    = {50},
  journal   = {Macromolecules},
  number    = {17},
  issn      = {1520-5835},
  doi       = {10.1021/acs.macromol.7b00947},
  pages     = {6679 -- 6689},
  year      = {2017},
  language  = {en}
}
@article{HagerHentschkeHojdisetal.2015,
  author    = {Hager, Jonathan and Hentschke, Reinhard and Hojdis, Nils and Karimi-Varzaneh, Hossein Ali},
  title     = {Computer Simulation of Particle-Particle Interaction in a Model Polymer Nanocomposite},
  series = {Macromolecules},
  volume    = {48},
  journal   = {Macromolecules},
  number    = {24},
  issn      = {1520-5835},
  doi       = {10.1021/acs.macromol.5b01864},
  pages     = {9039 -- 9049},
  year      = {2015},
  language  = {en}
}
@article{WallerBraunHojdisetal.2007,
  author    = {Waller, Mark P. and Braun, Heiko and Hojdis, Nils and B{\"u}hl, Michael},
  title     = {Geometries of Second-Row Transition-Metal Complexes from Density-Functional Theory},
  series = {Journal of Chemical Theory and Computation},
  volume    = {3},
  journal   = {Journal of Chemical Theory and Computation},
  number    = {6},
  issn      = {1549-9626},
  doi       = {10.1021/ct700178y},
  pages     = {2234 -- 2242},
  year      = {2007},
  language  = {en}
}
@article{SvaneborgKarimiVarzanehHojdisetal.2018,
  author    = {Svaneborg, Carsten and Karimi-Varzaneh, Hossein Ali and Hojdis, Nils and Fleck, Franz and Everaers, Ralf},
  title     = {Kremer-Grest Models for Universal Properties of Specific Common Polymer Species},
  series = {Soft Condensed Matter},
  journal   = {Soft Condensed Matter},
  number    = {1606.05008},
  year      = {2018},
  abstract  = {The Kremer-Grest (KG) bead-spring model is a near standard in Molecular Dynamic simulations of generic polymer properties. It owes its popularity to its computational efficiency, rather than its ability to represent specific polymer species and conditions. Here we investigate how to adapt the model to match the universal properties of a wide range of chemical polymers species. For this purpose we vary a single parameter originally introduced by Faller and M{\"u}ller-Plathe, the chain stiffness. Examples include polystyrene, polyethylene, polypropylene, cis-polyisoprene, polydimethylsiloxane, polyethyleneoxide and styrene-butadiene rubber. We do this by matching the number of Kuhn segments per chain and the number of Kuhn segments per cubic Kuhn volume for the polymer species and for the Kremer-Grest model. We also derive mapping relations for converting KG model units back to physical units, in particular we obtain the entanglement time for the KG model as function of stiffness allowing for a time mapping. To test these relations, we generate large equilibrated well entangled polymer melts, and measure the entanglement moduli using a static primitive-path analysis of the entangled melt structure as well as by simulations of step-strain deformation of the model melts. The obtained moduli for our model polymer melts are in good agreement with the experimentally expected moduli.},
  language  = {en}
}
@article{CheenakulaHoffstadtKrafftetal.2022,
  author    = {Cheenakula, Dheeraja and Hoffstadt, Kevin and Krafft, Simone and Reinecke, Diana and Klose, Holger and Kuperjans, Isabel and Gr{\"o}mping, Markus},
  title     = {Anaerobic digestion of algal-bacterial biomass of an Algal Turf Scrubber system},
  series = {Biomass Conversion and Biorefinery},
  volume    = {13},
  journal   = {Biomass Conversion and Biorefinery},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {2190-6823},
  doi       = {10.1007/s13399-022-03236-z},
  pages     = {15 Seiten},
  year      = {2022},
  abstract  = {This study investigated the anaerobic digestion of an algal-bacterial biofilm grown in artificial wastewater in an Algal Turf Scrubber (ATS). The ATS system was located in a greenhouse (50°54′19ʺN, 6°24′55ʺE, Germany) and was exposed to seasonal conditions during the experiment period. The methane (CH4) potential of untreated algal-bacterial biofilm (UAB) and thermally pretreated biofilm (PAB) using different microbial inocula was determined by anaerobic batch fermentation. Methane productivity of UAB differed significantly between microbial inocula of digested wastepaper, a mixture of manure and maize silage, anaerobic sewage sludge, and percolated green waste. UAB using sewage sludge as inoculum showed the highest methane productivity. The share of methane in biogas was dependent on inoculum. Using PAB, a strong positive impact on methane productivity was identified for the digested wastepaper (116.4\%) and a mixture of manure and maize silage (107.4\%) inocula. By contrast, the methane yield was significantly reduced for the digested anaerobic sewage sludge (50.6\%) and percolated green waste (43.5\%) inocula. To further evaluate the potential of algal-bacterial biofilm for biogas production in wastewater treatment and biogas plants in a circular bioeconomy, scale-up calculations were conducted. It was found that a 0.116 km2 ATS would be required in an average municipal wastewater treatment plant which can be viewed as problematic in terms of space consumption. However, a substantial amount of energy surplus (4.7-12.5 MWh a-1) can be gained through the addition of algal-bacterial biomass to the anaerobic digester of a municipal wastewater treatment plant. Wastewater treatment and subsequent energy production through algae show dominancy over conventional technologies.},
  language  = {en}
}
@article{MonakhovaDiehl2022,
  author    = {Monakhova, Yulia and Diehl, Bernd W.K.},
  title     = {Nuclear magnetic resonance spectroscopy as an elegant tool for a complete quality control of crude heparin material},
  series = {Journal of Pharmaceutical and Biomedical Analysis},
  volume    = {219},
  journal   = {Journal of Pharmaceutical and Biomedical Analysis},
  number    = {Article number: 114915},
  publisher = {Elsevier},
  address   = {New York, NY},
  issn      = {0731-7085},
  doi       = {10.1016/j.jpba.2022.114915},
  year      = {2022},
  abstract  = {Nuclear magnetic resonance (NMR) spectrometric methods for the quantitative analysis of pure heparin in crude heparin is proposed. For quantification, a two-step routine was developed using a USP heparin reference sample for calibration and benzoic acid as an internal standard. The method was successfully validated for its accuracy, reproducibility, and precision. The methodology was used to analyze 20 authentic porcine heparinoid samples having heparin content between 4.25 w/w \% and 64.4 w/w \%. The characterization of crude heparin products was further extended to a simultaneous analysis of these common ions: sodium, calcium, acetate and chloride. A significant, linear dependence was found between anticoagulant activity and assayed heparin content for thirteen heparinoids samples, for which reference data were available. A Diffused-ordered NMR experiment (DOSY) can be used for qualitative analysis of specific glycosaminoglycans (GAGs) in heparinoid matrices and, potentially, for quantitative prediction of molecular weight of GAGs. NMR spectrometry therefore represents a unique analytical method suitable for the simultaneous quantitative control of organic and inorganic composition of crude heparin samples (especially heparin content) as well as an estimation of other physical and quality parameters (molecular weight, animal origin and activity).},
  language  = {en}
}