Origin of Gas Porosity in Gold-Based Alloys Cast in Calcium Sulfate-Bonded Investment and Influence of Metal Oxide Acid–Base Properties on Calcium Sulfate Thermal Stability

The origin of gas-porosity in gold-based alloys produced via lost-wax casting in CaSO₄-bonded investment has been identified using a combination of microanalytical and thermal techniques. The occurrence of gas-porosity is related to the thermal decomposition of CaSO₄, which, with SiO₂, constitutes the investment material and decomposes at a temperature very close to the casting temperature of some typical gold alloys used for jewelry production. The thermal reaction generates SO₂, leading to gas-porosity and, therefore, to defective products. Furthermore, the results show the detrimental effect of thermal decomposition caused by the presence of ZnO, Cu₂O, CuO, NiO, and Ag₂O formed on the surface of the gold-based alloy during air melting or casting. Therefore, the solid-state thermal decomposition of CaSO₄ in the presence of other ceramic oxides has been investigated and found to be related to their surface acid–base properties, measured as isoelectric points on the solid surface.     

FLOW BOILING OF WATER AND n -HEPTANE IN MICRO CHANNELS

Heat transfer characteristics during flow boiling in micro channels with rectangular cross section were studied using a thermographic measuring method. The characteristic length of the channels investigated was varied in a region of 300 w m up to 700 w m. The channels were designed as Joule heating pipes. Thus, the evaporation was achieved under conditions of nearly constant heat fluxes at the heating wall of the channel. The thermographic measuring method was used to examine the wall temperature. The high spatial and temporal resolution of this thermographic measuring method makes it possible to detect the axial position of the different boiling regions. Furthermore, it allows conclusions to be made on which flow conditions occur in the different sections of the channel. Experimental results are shown with water and n -heptane as the fluid to be vaporized. The results of measurements are discussed and a correlation is given of the location where the dryout starts with the characteristic parameters. The dependence of the pressure drop in such channels on the technological parameters has also been presented.     

Potent inhibitors of the human UDP-glucuronosyltransferase 2B7 derived from the sesquiterpenoid alcohol longifolol

The tricyclic sesquiterpenol (+)-longifolol served as a lead structure for the design of inhibitors of the human UDP-glucuronosyltransferase (UGT) 2B7. Twenty-four homochiral and epimeric longifolol derivatives were synthesized and screened for their ability to inhibit the enzyme. The absolute configuration at the stereogenic center C1' was determined by X-ray crystallography and 2D NMR spectroscopy (gHSQC, gNOESY). The phenyl-substituted secondary alcohol 16 b (beta-phenyllongifolol) displayed the highest affinity toward UGT2B7, and its inhibitory dissociation constant was 0.91 nM. The mode of inhibition was rapidly reversible and competitive. The inhibitor was not glucuronidated by UGT2B7 or other hepatic UGTs, presumably as a result of the high steric demand exerted by the phenyl group. Inhibition assays employing 14 other UGT isoforms suggested that inhibitor 16 b was highly selective for UGT2B7.     

Multifunctional Magnetic Optical Sensor Particles with Tunable Sizes for Monitoring Metabolic Parameters and as a Basis for Nanotherapeutics

Magnetic optical sensor particles with multifunctional cores and shells are synthesized via a facile nanoprecipitation method and the subsequent modification of the particle shell. The hydrophobic particle core includes optical oxygen indicators, a light harvesting system, photosensitizers, and magnetic nanoparticles. Further functionalities are introduced by modifying the shell with enzymes, antibodies, multiple layers of polyelectrolytes, stimuli‐responsive polymers, and luminescent indicator dyes. The hydrodynamic diameter is tunable by varying different precipitation parameters.     

Generality and legibility in mobile manipulation

This article investigates methods for achieving more general manipulation capabilities for mobile manipulation platforms, which produce legible behavior in human living environments. To achieve generality and legibility, we combine two control mechanisms. First of all, experience- and observation-based learning of skills is applied to routine tasks, so that the repetitive and stereotypical character of everyday activity is exploited. Second, we use planning, reasoning, and search for novel tasks which have no stereotypical solution. We apply these ideas to the learning and use of action-related places, to the model-based visual recognition and localization of objects, and the learning and application of reaching strategies and motions from humans. We demonstrate the integration of these mechanisms into a single low-level control system for autonomous manipulation platforms.     

Reusable Localized Surface Plasmon Sensors Based on Ultrastable Nanostructures

Nanoparticle arrays created by nanosphere lithography are widely used in sensing applications since their localized surface plasmon resonances are extremely sensitive to changes in the local dielectric environment. A major drawback for any biologically oriented sensing application of conventionally produced particle arrays is the lack of stability of the nanoparticles in aqueous media and buffer solutions. Here, a robust and reusable nanoscale sensing platform based on localized surface plasmon resonances of gold nanoparticles embedded in a silicon dioxide matrix is presented. The architecture exhibits extremely high stability in aqueous environments and can be regenerated several times by simple mechanical cleaning of the surface. The platforms surface is ultraflat by design, thus making it an ideal substrate for any bio‐oriented sensing application.     

Substitution von Torf durch Holz in Pflanzsubstraten

Ohne Zusammenfassung     

Untersuchung zur PMDI-verteilung in spangemischen und Spanplatten

Microscopic studies on non-pressed chips glued with polymeric diphenylmethane diisocyanate (MDI) and on some particleboard cross-sections showed that due to its good wetting properties this glue effects a good thin-layer spread on the surface of the wooden chips. Due to capillar action MDI completely penetrates cracks in the chips. Moreover, there was evidence that MDI is capable of penetrating the cell walls. Particleoboard cross-sections showed that most of the earlywood portion in chip mixes was evidently completely saturated with MDI.