In-Operation Monitoring of the Soot Load of Diesel Particulate Filters: Initial Tests

Diesel particulate filters (DPF) are indispensable parts of modern automotive exhaust gas aftertreatment systems due to the stringent emissions legislation. For a fuel-efficient control strategy, it would be beneficial to determine directly and in-operation their actual trapped soot mass. Two novel approaches—based on the electrical conductivity of trapped soot particles—emerged recently. By measuring the electrical resistance between different single walls inside the filter, the soot load is determined with local resolution. The microwave-based technique is a contactless approach that gives an integral value depending on the soot mass in the DPF. We present investigations on loading and regeneration of DPFs in a dynamometer test bench applying both methods. The results are compared with each other and correlated with the differential pressure and the soot mass. Especially the microwave-based technique has a potential for serial application.     

Toughness Optimization of SBR Elastomers – Use of Fracture Mechanics Methods for Characterization

Elastomer materials are used in a wide application range and subjected to different loading from which failure of the material results. Because this failure is caused by initiation and propagation of cracks, the application of fracture mechanics methods for the assessment of the material is obvious. A short summary of the methods of technical fracture mechanics including possibilities of determination of crack resistance curves is given. Vulcanizates on the basis of SBR 1500 with various sulfur and carbon black contents were investigated. For describing the crack initiation and crack propagation behavior, several fracture mechanics examination methods were applied. Tear‐analyzer results were used to assess the crack propagation behavior under fatigue‐like loading conditions. Furthermore, for the characterization of the crack resistance of the materials under impact‐like loading conditions, instrumented tensile‐impact tests were performed. To obtain information about the initiation and propagation of a stable crack, quasi‐static fracture mechanics tests were applied. The results of the several tests are discussed in dependence on sulfur and carbon black contents. We found a non‐monotonous behavior of the toughness as a function of carbon black loading. An explanation is given in connection with a percolation‐like transition in filler morphology on larger length scales.

Schematic crack propagation curve for characterizing the fatigue behavior of the vulcanizates recorded in a TFA test.     

LAS glass–ceramic scaffolds by three-dimensional printing

Highly porous (>60% open porosity) glass–ceramic scaffolds with remarkable mechanical properties (compression strength of ～15 MPa) were produced by indirect 3D printing. Precursor glass powders were printed into 3D ordered structures and then heat treated to sinter and develop crystalline phases. The final glass–ceramic contained a β-spodumene solid solution together with a secondary phase of lithium disilicate.The precision of the printed geometry and the density of the struts in the scaffold depended on several processing parameters (e.g. powder size and flowability, layer thickness) and were improved by increasing the binder saturation and drying time. Two types of powders with different particle size distribution (PSD) and flowability were used. Powders with a larger PSD, could be processed within a wider range of printing parameters due to their good flowability; however, the printing precision and the struts density were lower compared to the scaffolds printed using the powder in a smaller average PSD.     

Identification and Structure–Activity Relationship Studies of Small‐Molecule Inhibitors of the Methyllysine Reader Protein Spindlin1

The methyllysine reader protein Spindlin1 has been implicated in the tumorigenesis of several types of cancer and may be an attractive novel therapeutic target. Small‐molecule inhibitors of Spindlin1 should be valuable as chemical probes as well as potential new therapeutics. We applied an iterative virtual screening campaign, encompassing structure‐ and ligand‐based approaches, to identify potential Spindlin1 inhibitors from databases of commercially available compounds. Our in silico studies coupled with in vitro testing were successful in identifying novel Spindlin1 inhibitors. Several 4‐aminoquinazoline and quinazolinethione derivatives were among the active hit compounds, which indicated that these scaffolds represent promising lead structures for the development of Spindlin1 inhibitors. Subsequent lead optimization studies were hence carried out, and numerous derivatives of both lead scaffolds were synthesized. This resulted in the discovery of novel inhibitors of Spindlin1 and helped explore the structure–activity relationships of these inhibitor series.     

Distortion-free laser beam shaping for material processing using a digital micromirror device

Digital micromirror devices (DMD) are increasingly used in laser-based manufacturing for a maskless beam shaping in order to realize simultaneous 2D/3D material processing. Thereby, the DMD has to be irradiated under a sharp angle to achieve acceptable projection quality with negligible distortion phenomena. In this article, we present a novel setup for DMD-based laser material processing. It enables the irradiation under large angles (up to 60\(^{\circ }\)), the reduction of optical elements as well as machine size. Occurring optical distortions during the amplitude-based laser beam shaping are characterized. To eliminate these phenomena, we implement an optical modelling of the DMD patterns, taking into account the propagation through the tilted interfaces. The resulting imaging of different desired shapes is verified experimentally for its geometrical properties such as length, radius and aspect ratio. Thereby, an angle-dependent correction and high shape accuracy of the image projection is shown. This novel arrangement may have applications in direct laser writing and photochemical machining.     

Separation of Extracellular Esterases from Pellet Cultures of the Basidiomycete Pleurotus sapidus by Foam Fractionation

Two extracellular esterases were produced in submerged cultures of the basidiomycete Pleurotus sapidus. A foam fractionation device was designed and employed for the isolation of the esterolytic enzymes. The recovery of enzyme activity in the liquefied foam strongly depended on the superficial gas velocity. High purification and enrichment factors (E _a = 62.0, P = 15.5) were achieved using nitrogen at 1.87 cm min⁻¹ within 100 min. Increasing the superficial gas velocity to 2.49 cm min⁻¹ improved the recovery of total esterase activity in the foam to >95% at the expense of reduced enrichment and purification factors. Differences in their physicochemical characteristics resulted in differing foaming properties of the two esterases secreted by P. sapidus. By variation of the pH value of the culture medium and addition of Triton X-100, both esterases were successively and quantitatively transferred into the foam in a two-step fractionation process.     

Characterization of Cu/CeO2/γ-Al2O3 Thin Film Catalysts by Thermal Desorption Spectroscopy

Thermal desorption spectroscopy (TDS) under ultra high vacuum (UHV) condition has been used to investigate the desorption characteristics of Cu/CeO₂/γ-Al₂O₃ thin film catalysts coated onto the microchannel of a microreactor. TDS results demonstrate that surface desorption profiles and chemical properties (acid–base and redox properties) are remarkably influenced by the catalyst composition, i.e. the loading of copper and ceria. The enhanced basicity with the increase of ceria loading and the decrease of copper loading is evident from the shifted desorption maximum of CO₂ in TDS spectra. Three oxygen species, ranging from weakly bound oxygen desorbed at low temperature to the strongly held lattice oxygen desorbed at high temperature, are easily discernible and clearly identified by O₂ TDS spectra, depending on the catalyst compositions. The concomitant thermal desorption of O₂, CO₂, and H₂O at low temperature indicates the unique chemical properties of copper/ceria catalyst with appropriate copper and ceria contents. The observed low-temperature feature is ascribed to the role of porthole of copper/ceria interfacial area for several desorbed species. The weakly bound oxygen species is attributed to the enhanced abundance of copper/ceria interfacial anionic vacancies created by the intimate contact between copper and ceria entities and its impact on steam reforming of methanol (SRM) reaction is tentatively discussed in terms of reverse oxygen spillover.     

Synthesis and antiapoptotic activity of a novel analogue of the neutral sphingomyelinase inhibitor scyphostatin

The enantioselective synthesis of an analogue of scyphostatin, a potent inhibitor of the neutral sphingomyelinase, is described. The synthesis starts with cyclohexanone and a protected D-serine derivative. The key step is an asymmetric hydroxylation to access a hydroxycyclohexanone, which is transformed into a substituted hydroxycyclohexenone. This is converted into the scyphostatin analogue 14, a chemically and metabolically stabilised compound lacking the epoxy function of the natural congener and carrying a palmitic acid group instead of the native trienoyl residue. An evaluation of the biological activity of 14 revealed neutral sphingomyelinase inhibition in several in vivo test systems (monocytes, macrophages, hepatocytes) monitoring antiapoptotic effects and the inversion of phorbolester-induced translocation of green fluorescent protein labelled kinase (protein kinase C-alpha).     

ZSM-5 zeolite films on Si substrates grown by in situ seeding and secondary crystal growth and application in an electrochemical hydrocarbon gas sensor

ZSM-5 zeolite films were grown on Si substrates by a two-step hydrothermal synthesis consisting of in situ seeding and secondary crystal growth. The films were 8–13 μm thick and partly oriented with the c-axis perpendicular to the substrate surface. After ion exchange with sodium ions, one film was applied as solid electrolyte in a potentiometric hydrocarbon gas sensor. A fast and reversible voltage response of the sensor to varying propane concentrations (100 ppm – 10%) was observed in O₂/CO₂/N₂ gas mixtures at 723 K.     

Increasing recyclability of PC,ABS and PMMA: Morphology and fracture behavior of binary and ternary blends

Binary and ternary blends of PC, ABS, and PMMA were studied. The blends were produced from original and recycled materials by melt mixing in a wide range of compositions. Instrumented Charpy impact testing, tensile testing, rheology investigations, and electron microscopy were carried out to determine the relationship between the deformation and fracture behavior, blend composition, morphology, and processing parameters. Resistance against unstable crack propagation was evaluated using the concepts of J‐integral and crack‐tip‐opening displacement (CTOD). The transition from ductile elastic‐plastic to brittle‐linear elastic fracture behavior was observed in the case of PC/ABS/PMMA blend at 10% of PMMA. Reprocessing had only a slight influence on the deformation and fracture behavior of the recycled blends. The blends produced from recycled materials proved to be competitive with the original pure materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008