Simultaneous Measurements of Temperature and CO Concentration in Stagnation Stabilized Flames

An impinging jet burner was developed to investigate flame-wall interactions (FWI) using laser based diagnostics. CO concentrations were measured with two-photon laser-induced fluorescence (LIF) in combination with coherent anti-Stokes Raman spectroscopy (CARS) gas phase temperature measurements. Besides being the principal factor in chemical kinetics, temperature data is required to correct the CO LIF data for various factors like density variation, quenching and variation in the Boltzmann population. Phosphor thermometry was used to determine surface temperatures of the wall and to estimate the heat flux. In an parameter study Reynolds numbers and fuel equivalence ratio were varied.     

Thermodynamic model formulation for viscoplastic solids as general equations for non-equilibrium reversible–irreversible coupling

Thermodynamic models for viscoplastic solids are often formulated in the context of continuum thermodynamics and the dissipation principle. The purpose of the current work is to show that models for such material behavior can also be formulated in the form of a General Equation for Non-Equilibrium Reversible–Irreversible Coupling (GENERIC), see, e.g., Grmela and Öttinger (Phys Rev E, 56:6620–6632, 1997), Öttinger and Grmela (Phys Rev E, 56:6633–6655, 1997), Grmela (J Non-Newtonian Fluid Mech, 165:980–986, 2010). A GENERIC combines Hamiltonian-dynamics-based modeling of time-reversible processes with Onsager–Casimir-based modeling of time-irreversible processes. The result is a model for the approach of non-equilibrium systems to thermodynamic equilibrium. Originally developed to model complex fluids, it has recently been applied to anisotropic inelastic solids in Eulerian (Hütter and Tervoort, in J Non-Newtonian Fluid Mech, 152:45–52, 2008; Hütter and Tervoort, in J Non-Newtonian Fluid Mech, 152:53–65, 2008; Hütter and Tervoort, in Adv Appl Mech, 42:254–317, 2008) and Lagrangian (Hütter and Svendsen, in J Elast 104:357–368, 2011) settings, as well as to damage mechanics. For simplicity, attention is focused in the current work on the case of thermoelastic viscoplasticity. Central to this formulation is a GENERIC-based form for the viscoplastic flow rule. A detailed comparison with the formulation based on continuum thermodynamics and the dissipation principle is given.     

A Study of Microscale Gas Trapping Using Etched Silicon Micromodels

Immobilization and trapping of carbon dioxide (CO₂) enhances the security of geological storage. Trapping mechanisms have been characterized in four groups: structural, residual, dissolution, and mineralization. While structural trapping acts immediately when injection starts and is well investigated, the contribution of residual and dissolution trapping increases over storage time and these contributions need to be better understood for better predictions. This paper focuses on an experimental pore-scale investigation of residual and capillary trapping. CO₂?Cwater imbibition experiments were conducted in micromodels whose homogenous pore space is geometrically and topologically similar to Berea sandstone. Microvisual data, photographs and video footage, describes the trapping mechanism and, especially, the disconnection and shrinkage of the CO₂ phase. Results show that depending on the flow rate of the imbibing water different trapping mechanisms are observed. Lower flow rates, comparable to the trailing edge of a CO₂ plume, lead to more snap-off events and greater trapped residual saturation, whereas rates comparable to the near wellbore area during enhanced sequestration showed displacement of gas bubbles and greater dissolution that ultimately leads to very low or zero gas saturations. Furthermore, complete dissolution events showed that homogenous as well as heterogeneous dissolution occurs. Whereas the latter is subdivided into microbubble formation and dissolution on crevices or pore roughness, the former occurs without the influence of pore walls. Based on the observations we suggest that the type of rock and its roughness as well as the fines present at the CO₂ brine interface are important factors determining the dissolution mechanism.     

3D-PTV measurements in a plane Couette flow

Genuine plane Couette flow is hard to realize experimentally, and no applications of modern spatially resolving measurement techniques have been reported for this flow so far. In order to resolve this shortcoming, we designed and built a new experimental facility and present our first results here. Our setup enables us to access the flow via 3D particle tracking velocimetry and therefore to obtain truly three-dimensional flow fields for the first time experimentally in plane Couette flow. Results are analyzed in terms of basic flow properties, and a clear distinction of flow regimes (laminar for Re < 320, transitional for 320 < Re < 400, and turbulent when Re > 400) could be made. Comparison with DNS data shows good agreement in the turbulent regime and builds trust in our data. Furthermore, vortical coherent structures are studied in detail with the additional help of kalliroscope imaging, and the typical vortex spacing is determined to be roughly one gap width. As a noteworthy result, we find that the onset of the turbulent regime coincides with the range of Reynolds numbers at which a distance of 100 wall units is comparable to the gap width.     

Stable Peptides Instead of Stapled Peptides: Highly Potent αvβ6‐Selective Integrin Ligands

The αvβ6 integrin binds the RGD‐containing peptide of the foot and mouth disease virus with high selectivity. In this study, the long binding helix of this ligand was downsized to an enzymatically stable cyclic peptide endowed with sub‐nanomolar binding affinity toward the αvβ6 receptor and remarkable selectivity against other integrins. Computational studies were performed to disclose the molecular bases underlying the high binding affinity and receptor subtype selectivity of this peptide. Finally, the utility of the ligand for use in biomedical studies was also demonstrated here.     

Raffinose + Raffinase = Raffinade: Raffiniert!

Raffinose has been obtained by extraction with 50% ethanol from the seeds of the Sweet Blue Lupine and purified first via a Cation exchange column and finally by analytical HPLC using a RI‐detector. All analytical spectra were recorded and are reproduced either in the main part or in the supporting information. The NMR‐ and mass‐spectra have been interpreted and compared with theoretical calculations of the ¹³C chemical shifts. The project is a follow up of the recent book “Classics in Spectroscopy” by S. Berger und D. Sicker (Wiley‐VCH 2009).     

Aluminum-doped ZnO nanoparticles: gas-phase synthesis and dopant location

Printed electronics, as an extension to conventional electronics, has grown considerably for decades. At this moment, therefore, tracing the development of this technology up to the present will provide researchers and R&D planners with better understanding of the technology’s evolving characteristics and insights for further R&D directions. This paper carries out two bibliographic analyses to study the technology development life cycle and the technological knowledge within the area of printed electronics. First, we fit a growth curve to yearly patent registration data, thereby calculating several indicators, including the current technological maturity ratio, the number of potential future patents and the expected remaining life. Second, we identify the core and brokering technology classes within the overall technology network of printed electronics by combining patent co-classification analysis and social network analysis. As a result, we could obtain some findings from the inventional point of view; the technological development of printed electronics has entered the maturity stage, and the expected remaining life was 8.5 years as of the beginning of 2013. In addition, we identified several technology areas that have the high importance to act as both core and brokering technologies, apparatus for metal working, anti-inductive structures, and electronic circuit control systems.     

Poly(2‐vinyl pyridine)‐block‐Poly(ethylene oxide) Featuring a Furan Group at the Block Junction—Synthesis and Functionalization

Furfuryl glycidyl ether (FGE) represents a highly versatile monomer for the preparation of reversibly cross‐linkable nanostructured materials via Diels–Alder reactions. Here, the use of FGE for the mid‐chain functionalization of a P2VP‐b‐PEO diblock copolymer is reported. The material features one furan moiety at the block junction, P2VP₆₈‐FGE‐b‐PEO₃₉₀, which can be subsequently addressed in Diels–Alder reactions using maleimide‐functionalized counterparts. The presence of the FGE moiety enables the introduction of dyes as model labels or the formation of hetero‐grafted brushes as shell on hybrid Au@Polymer nanoparticles. This renders P2VP₆₈‐FGE‐b‐PEO₃₉₀, a powerful tool for selective functionalization reactions, including the modification of surfaces.

     

Utilizing Stretch‐Tunable Thermochromic Elastomeric Opal Films as Novel Reversible Switchable Photonic Materials

In this work, the preparation of highly thermoresponsive and fully reversible stretch‐tunable elastomeric opal films featuring switchable structural colors is reported. Novel particle architectures based on poly(diethylene glycol methylether methacrylate‐co‐ethyl acrylate) (PDEGMEMA‐co‐PEA) as shell polymer are synthesized via seeded and stepwise emulsion polymerization protocols. The use of DEGMEMA as comonomer and herein established synthetic strategies leads to monodisperse soft shell particles, which can be directly processed to opal films by using the feasible melt‐shear organization technique. Subsequent UV crosslinking strategies open access to mechanically stable and homogeneous elastomeric opal films. The structural colors of the opal films feature mechano‐ and thermoresponsiveness, which is found to be fully reversible. Optical characterization shows that the combination of both stimuli provokes a photonic bandgap shift of more than 50 nm from 560 nm in the stretched state to 611 nm in the fully swollen state. In addition, versatile colorful patterns onto the colloidal crystal structure are produced by spatial UV‐induced crosslinking by using a photomask. This facile approach enables the generation of spatially cross‐linked switchable opal films with fascinating optical properties. Herein described strategies for the preparation of PDEGMEMA‐containing colloidal architectures, application of the melt‐shear ordering technique, and patterned crosslinking of the final opal films open access to novel stimuli‐responsive colloidal crystal films, which are expected to be promising materials in the field of security and sensing applications.

     

Nuclear inelastic scattering studies on a dinuclear iron(II) spin crossover complex

The vibrational properties of the (high-spin)-(high-spin) and the (high-spin)- (low-spin) states of the dinuclear Fe(II) spin crossover complex[{Fe(L-N₄Me₂)}₂(BiBzIm)](ClO₄)₂·2EtCN¹ have been studied by means of nuclear inelastic scattering. At a temperature of 80 K typical low spin marker bands are detected in the region around 400 cm^?1, these bands almost completely disappear after increasing temperature to 190 K. Corresponding density functional theory calculations using the functional B3LYP* and the basis set CEP-31G reproduce the experimental data and thus allow a deeper understanding of the vibrational properties of dinuclear Fe(II) spin crossover complexes.