Investigation and development of gravity separators with a standardized experimental setup

This contribution presents a standardized experimental setup for the development of gravity separators. Two different optical measurement techniques for the characterization of the inlet and outlet dispersion with a droplet spectrum of 20-2000 μm are used. The settling behaviour in a standardized batch settling test (ERICAA cell) serves as a basis for predicting the drop diameter resolved separation efficiency of a horizontal continuous separator. The latter (DN150, length 0.65 m) was operated and monitored with a phase fraction of up to 15% and a load of up to 17.0 m³ m⁻² h⁻¹. A paraffin oil with a viscosity of 10 mPa s was the dispersed and water the continuous phase. Sauter mean diameters of dispersions measured inline show a good agreement with those calculated from batch settling tests. Additionally, the modelled separation efficiencies are compared to the experimental results produced with the continuous separator.     

Ecologic Potential for Flexible Methanol Production from Steel Mill Off-gases

Methanol production is one promising way to minimize the ecological impact of the conventional steelmaking process. This synthesis needs additional hydrogen, preferably produced from a green power source. In this paper, the influence of different power supply scenarios, gas storage volumes, and hydrogen production capacities on the overall carbon saving potential – defined as carbon binding ratio – from a flexible methanol production case will be investigated. A mixed-integer linear programming model with rolling horizon is used to calculate the optimal production plan.     

On Limitations of Structured (Deterministic) DNNFs

Theory of Computing Systems - The study of representations for propositional theories has been a central subject in knowledge compilation. Many known representations of propositional knowledge...     

Micro- to macroscale magnetic resonance imaging of glioma

Magnetic Resonance Materials in Physics, Biology and Medicine -     

Antagonistic Interactions Mediated by Marine Bacteria: The Role of Small Molecules

Marine bacteria are known to produce a wide variety of structurally diverse and biologically active secondary metabolites. Considerably less is known about the ecological functions of these compounds, in part due to methodological challenges associated with this field of research. Here, we review the antagonistic activities mediated by marine bacteria with a focus on activities linked to structurally defined secondary metabolites. Bacterial antagonism has been documented against other marine bacteria as well as eukaryotes, and includes antibiosis, the inhibition of quorum sensing, larval settlement deterrence, and defense against predation. These compounds likely play important ecological roles that ultimately affect ecosystem structure and function, however, much remains to be learned before these roles can be fully appreciated. Recent technological advances coupled with a better understanding of the diverse processes mediated by secondary metabolites provide new opportunities to expand our understanding of the chemical ecology of bacterial antagonism in the marine environment.     

Production of 1‐Octanol from n‐Octane by Pseudomonas putida KT2440

A two‐phase biotransformation process for selective hydroxylation of n‐octane to 1‐octanol via Pseudomonas putida KT2440 harboring heterologously expressed P450 monooxygenase from Mycobacterium marinum is presented. Maximum cell‐specific conversion rates of 12.7 mg_octanol g_CDWh^–1 were observed not only in shaking flasks but also in 3.7‐L‐bioreactor studies. The bioreactor experiments were performed avoiding explosive gas mixtures by lowering volumetric power input, aeration rates and substrate concentrations. Based on a stoichiometric network of P. putida KT2440 topological studies were carried out. As a conclusion, potential limitations of NAD(P)H and/or ATP supply at production conditions can be excluded. Hence, the great potential of the host for further increasing conversion is outlined.     

Observation of liquid solution volume expansion during particle precipitation in the supercritical CO2 antisolvent process

An optical measurement technique, which is based on the Foerster resonant energy transfer (FRET) between two different dye molecules, has been applied successfully to observe volume expansion of a liquid solution, when it is pressurized with CO₂. Rhodamine-B and Rhodamine-700 were dissolved in ethanol to form the FRET active dye solution. In a first “prove of principle” experiment, the sensitivity of the FRET efficiency towards volume expansion was demonstrated by pressurizing the liquid dye solution in a cuvette with CO₂. From the rise of the meniscus of the solution inside the cuvette as a function of CO₂ pressure, the simultaneously acquired FRET spectra could be correlated with the volume expansion of the dye solution. In a second experiment, the dye solution was injected into CO₂ at different supercritical antisolvent operation pressures. FRET spectra were recorded 3 mm downstream of the injector nozzle, always upstream of the breakup of the injected liquid solution. At pressures below the thermodynamic mixture critical pressure (7.9 MPa @ 313 K) of the system ethanol/CO₂ no liquid phase volume expansion was observed. At pressures between the thermodynamic and the dynamic mixture critical pressure (8.5 MPa @ 313 K) of the same system, volume expansion could be evidenced before the breakup of the injected liquid solution.