Release of K,Cl, and S during combustion and co-combustion with wood of high-chlorine biomass in bench and pilot scale fuel beds

Studies of the release of critical ash-forming elements from combustion of biomass are typically conducted with small sample masses under well controlled conditions. In biomass combustion on a grate, secondary recapture and release reactions in the fuel-bed may affect the overall release and partitioning of these elements. Earlier work by the authors on the release of K, Cl, and S from a high-chlorine biomass (corn stover) in a lab-scale setup is, in the present work, supplemented with novel results from a bench-scale fixed bed reactor and a 100 kW moving grate pilot facility. The results from the bench-scale reactor indicate that S and K release are not significantly affected by secondary reactions, while Cl is partly recaptured by secondary reactions in the char. A linear increase in K-release was observed from 50% at 906 °C to almost 80 wt.% at 1234 °C when firing only corn stover. A similar release profile was observed for Cl, from 65% to nearly 100%. Complete release of S was achieved at 1234 °C with a linear increase from 70% at 906 °C. Co-combustion of corn stover with low-Cl wood chips served to increase the bed temperature, resulting in complete and close to complete release of Cl and S, respectively. An increase in the relative K-release was observed when increasing the wood chip fraction from 40% to 100% (energy basis). Pilot scale flue gas results indicate that the share of Cl released as HCl decreases towards 0% as the share of wood chips is increased towards 100%. Hence, co-combustion of corn stover with wood chips is expected to decrease the absolute release of KCl due to the lower feedstock quantity of Cl, however, increase the relative release of Cl as KCl.     

Reelin expression during embryonic development of the pig brain

Background  

Reelin is an extracellular glycoprotein of crucial importance in the developmental organisation of neurons in the mammalian cerebral cortex and other laminated brain regions. The pig possesses a gyrencephalic brain that bears resemblance to the human brain. In order to establish an animal model for neuronal migration disorders in the pig, we have studied the expression pattern and structure of Reelin during pig brain development.     

Wall-PIV as a near wall flow validation tool for CFD: Application in a pathologic vessel enlargement (aneurysm)

Flow visualization of a near wall flow is of great importance in the field of biofluid mechanics in general and for studies of pathologic vessel enlargements (aneurysms) particularly. Wall shear stress (WSS) is one of the important hemodynamic parameters implicated in aneurysm growth and rupture. The WSS distributions in anatomically realistic vessel models are normally investigated by computational fluid dynamics (CFD). However, the results of CFD flow studies should be validated. The recently proposed Wall-PIV method was first applied in an enlarged transparent model of a cerebri anterior artery terminal aneurysm made of silicon rubber. This new method, called Wall-PIV, allows the investigation of a flow adjacent to transparent surfaces with two finite radii of curvature (vaulted walls). Using an optical method which allows the observation of particles up to a predefined depth enables the visualization solely of the boundary layer flow. This is accomplished by adding a specific molecular dye to the fluid which absorbs the monochromatic light used to illuminate the region of observation. The results of the Wall-PIV flow visualization were qualitatively compared with the results of the CFD flow simulation under steady flow conditions. The CFD study was performed using the program FLUENT®. The results of the CFD simulation were visualized using the line integral convolution (LIC) method with a visualization tool from AMIRA®. The comparison found a very good agreement between experimental and numerical results.     

Geometry and transport in a model of two coupled quadratic nonlinear waveguides

This paper applies geometric methods developed to understand chaos and transport in Hamiltonian systems to the study of power distribution in nonlinear waveguide arrays. The specific case of two linearly coupled chi((2)) waveguides is modeled and analyzed in terms of transport and geometry in the phase space. This gives us a transport problem in the phase space resulting from the coupling of the two Hamiltonian systems for each waveguide. In particular, the effect of the presence of partial and complete barriers in the phase space on the transfer of intensity between the waveguides is studied, given a specific input and range of material properties. We show how these barriers break down as the coupling between the waveguides is increased and what the role of resonances in the phase space has in this. We also show how an increase in the coupling can lead to chaos and global transport and what effect this has on the intensity.     

Observation of hotspot in BSCCO thin film structure by fluorescent thermal imaging

Hotspot formation is observed in a structured thin superconducting film of Bi₂Sr₂CaCu₂O_x (BSCCO) using the fluorescent thermal imaging technique. The BSCCO film is deposited on SrTiO₃ (STO) and has a superconducting transition at 80 K. A film of rare-earth doped polymer film deposited directly on the superconductor is used as thermal sensor down to 4 K.     

Combustion in a horizontal channel partially filled with a porous media

Experiments were carried out to investigate the combustion propagation phenomenon in a horizontal channel partially filled with ceramic-oxide spherical beads. A 1.22 m long, 43 mm nominally thick layer of spherical beads is located at the ignition end of a 2.44 m long, 76 mm square channel. Tests were performed with 6.4 and 12.7 mm diameter beads. A flame is ignited at the bead end wall by an automotive spark ignition system. Flame propagation and pressure measurements are obtained via ionization probes and piezoelectric pressure transducers mounted on the top and bottom surfaces of the channel. High-speed schlieren video was used to visualize the structure of the explosion front. Experiments were performed with a 31% nitrogen diluted stoichiometric methane–oxygen mixture at room temperature and at an initial pressure in the range of 15–50 kPa. For initial pressures of 15 and 20 kPa the flame accelerates to a velocity close to the speed of sound in the combustion products. For initial pressure of 30 kPa and higher DDT occurs in the gap above the bead layer. An explosion front propagating at a velocity just under the CJ detonation velocity is detected in the bead layer even though the bead layer pore size is much smaller than the detonation cell size. It is demonstrated that flame propagation within the bead layer is the driving force behind the very rapid flame acceleration observed, however the DDT event occurring in the gap above the bead layer is not affected by the bead layer porosity. Schlieren video indicates that the structure of the explosion front varies across the channel height and with propagation distance down the channel.     

Rasterelektronenmikroskopische Kontrastuntersuchungen an Germanium-Einkristallfolien

Statements made after scanning electron microscope contrast investigations on the geometrical and physical properties of thin, foil-like crystal regions strongly depend on the utilized interaction between electron probe and specimen. At the example of germanium single crystal foils of a thickness of only a few hundred Å in thinned regions the image contrasts resulting from secondary, backscattered, and absorbed electrons within an accelerating voltage range of between 15 and 45 kV are discussed. This is done based on the present knowledge of the ejecting mechanisms of the three interactions. It is not yet determined whether by means of adequate calibration methods a technique for evaluation of the thickness of such specimens can be developed from this.     

Mechanical,Barrier, Antioxidant and Antimicrobial Properties of Alginate Films: Effect of Seaweed Powder and Plasma-Activated Water

The incorporation of natural fillers such as seaweed may potentially enhance the properties of biopolymer films. In this study, we investigated the effect of seaweed powder as a bio-filler in alginate-based films at different concentrations (10, 30, and 50%, w/w alginate) and particle sizes (100 and 200 μm) on the mechanical, barrier, antioxidant, and antimicrobial properties of alginate which are essential for food packaging applications. Initially, mechanical properties of the alginate films prepared at different temperatures were evaluated to find the optimal temperature for preparing alginate solution. The addition of seaweed powder did not have any positive effect on the mechanical properties of the alginate films. However, the barrier (water vapor transmission rate) and antioxidant properties were improved with the addition of seaweed filler regardless of concentration. In addition, selected films were prepared in plasma-activated water (PAW). The mechanical properties (tensile strength, but not elongation at break) of the films prepared with PAW improved compared to the films prepared in distilled water, while a significant decrease was observed when incorporated with the seaweed filler. The films prepared in PAW also showed improved barrier properties compared to those prepared in distilled water. The antimicrobial activity of the alginate-seaweed film-forming solution was in general more pronounced when prepared with PAW and stored at 10 °C, particularly at the highest concentration of the film-forming solution (83.3% v/v). A more pronounced inhibitory effect was observed on the Gram-positive S. aureus than on the Gram-negative E. coli, which has been attributed to the different composition and structure of the respective cell walls. This study has demonstrated the potential of seaweed filler in combination with PAW towards enhanced functionality and bioactivity of alginate films for potential food packaging applications.