Crystal structure refinement and hydration behaviour of doped tricalcium aluminate

In this paper analytical evidence on crystal structure and hydration behaviour of C₃A solid solutions with MgO, SiO₂, Fe₂O₃, Na₂O and K₂O is given. Samples were prepared using an innovative sol-gel process as precursor, examined by X-ray powder diffraction, infra-red spectroscopy and the crystal structure was refined by the Rietveld method. A significant shift of lattice parameters was found for C₃A solid solutions with SiO₂, Fe₂O₃ or Na₂O but only minor changes were detected for K₂O. The hydration of C₃A solid solutions in the absence of CaSO₄ was accelerated for samples doped with SiO₂ or K₂O and it was retarded in the case of MgO, Fe₂O₃ or Na₂O. The hydration in the presence of CaSO₄ was accelerated when C₃A was doped with K₂O or Na₂O, whereas Fe₂O₃ strongly retarded the hydration. The doping with SiO₂ nearly had no influence on the hydration, the effect of MgO was not straight forward.     

In Situ Study on the Generation of Radiation Damage in Cubic-Zirconia in the High-Voltage Electron Microscope

Deformed cubic-zirconia single crystals have been irradiated in the high-voltage electron microscope at room temperature. Prismatic dislocation loops of extrinsic character grow on {111} planes as secondary radiation damage, preferentially along dislocations. At about 200°C, the loops grow much faster and instantaneously transform into dislocations with a a /2〈110〉-type Burgers vector.     

Applications of SQL for informetric frequency distribution processing

Summary  Many informetric data types lend themselves to ready adaptation to relational DBMS environments for storage and processing. SQL, the standard language used for constructing and querying relational databases, provides useful tools for processing informetric data. The author demonstrates the applications and some limitations of SQL for efficient organization and tabulation of raw informetric data.     

„Konvergenzargumentation“—Bastion gegen das Forschungsklonen

Ohne Zusammenfassung     

Ceramic Matrix Composites Life Cycle Testing Under Reusable Launcher Environmental Conditions

This article focuses on the thermal protection system (TPS) and hot structures based on carbon fiber-reinforced SiC (C/SiC) material, which protects the high thermal-loaded areas and control surfaces of a reusable launch vehicle (RLV). The goal of the test program is the evaluation of the lifetime of different types of TPS under reusability aspects for RLV application, reflecting the re-entry environments together with the effect of impacts from low-speed impact, rain erosion, and hail core impact. The test results of the C/SiC samples with the self-healing oxidation protection system showed very promising results concerning reusability and lifetime.     

Identification of Host Fruit Volatiles from Snowberry (<Emphasis Type="Italic">Symphoricarpos albus</Emphasis>), Attractive to <Emphasis Type="Italic">Rhagoletis zephyria</Emphasis> Flies from the Western United States

A mixture of behaviorally active volatiles was identified from the fruit of snowberry, Symphoricarpos albus laevigatus, for Rhagoletis zephyria flies reared from snowberry fruit. A nine-component blend containing 3-methylbutan-1-ol (3%), dimethyl trisulfide (1%), 1-octen-3-ol (40%), myrcene (8%), nonanal (9%), linalool (13%), (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT, 6%), decanal (15%), and β-caryophyllene (5%) was identified that gave consistent electroantennogram activity and was behaviorally active in flight tunnel tests. In other flight tunnel assays, snowberry flies from two sites in Washington state, USA, displayed significantly greater levels of upwind oriented flight to sources with the snowberry volatile blend compared with previously identified volatile blends from domestic apple (Malus domestica) and downy hawthorn (Crataegus mollis) fruit from the eastern USA, and domestic apple, black hawthorn (C. douglasii) and ornamental hawthorn (C. monogyna) from Washington state. Selected subtraction assays showed that whereas removal of DMNT or 1-octen-3-ol significantly reduced the level of upwind flight, removal of myrcene and β-caryophyllene, or dimethyl trisulfide alone did not significantly affect the proportion of upwind flights. Our findings add to previous studies showing that populations of Rhagoletis flies infesting different host fruit are attracted to unique mixtures of volatile compounds specific to their respective host plants. Taken together, the results support the hypothesis that differences among flies in their behavioral responses to host fruit odors represent key adaptations involved in sympatric host plant shifts, contributing to host specific mating and generating prezygotic reproductive isolation among members of the R. pomonella sibling species complex.     

Micro-/Macroporous Ceramics from Preceramic Precursors

Porous silicon oxycarbide (SiOC) ceramics in particular bulk and cellular structures are produced via polymer pyrolysis. By using optimal pyrolysis parameters (i.e., heating rate, maximum temperature) the addition of either solid fillers or chemically active additives is efficient in preventing the collapse of pore structure and controlling pore formation through decomposition. Fast pyrolysis can lead to crack formation and a loss of specific surface area at temperatures above 600°C, whereas slow pyrolysis is able to preserve mesopores up to 1200°C combined with high surface areas. These SiOC ceramics with bimodal pore size distribution are potential candidates for adsorption/separation processes under severe conditions.     

Shear Strength Measurement of AV119 Epoxy‐Joined SiC by Different Torsion Tests

The results of an experimental investigation on epoxy‐joined silicon carbide tested in shear mode by seven different configurations of torsion tests are presented and compared to results obtained by asymmetric four‐point bending. All samples have been joined by an epoxy adhesive (Araldite AV119) chosen to obtain several joined samples in a reasonable time. Advantages and disadvantages of each configuration are discussed with the aim of finding a suitable method to measure the shear strength of joined components.     

Three component terpolymer and IPN hydrogels with response to stimuli

Two different types of multi-stimuli-shrinking hydrogels were synthesized (IPNs and terpolymeric hydrogels) by properly polymerizing N-isopropylacrylamide, 2-hydroxyethyl methacrylate and 2-acrylamido-2-methylpropanesulfonic acid in various mutual ratios and different synthetic orders. Both classical (CP) and frontal (FP) polymerizations were used and the resulting material properties compared. The best compositions and synthetic routes were found and the swelling, morphological and thermal material properties were studied. The results show that some IPNs exhibit marked stimuli-shrinking properties while some terpolymers present an opposite behavior. IPNs swell more than terpolymers and show a sharper stimuli-response, with a larger swelling ratio variation. In addition, FP allowed obtaining samples with the same characteristic of CP materials, but with significant preparation advantages. It has been demonstrated that by varying monomer mutual ratio, synthetic technique (FP or CP) and structural architecture (terpolymers or IPNs), different materials having peculiar properties and characteristics can be obtained.     

A combined method for enclosing all solutions of nonlinear systems of polynomial equations

We consider the problem of finding interval enclosures of all zeros of a nonlinear system of polynomial equations. We present a method which combines the method of Gröbner bases (used as a preprocessing step), some techniques from interval analysis, and a special version of the algorithm of E. Hansen for solving nonlinear equations in one variable. The latter is applied to a triangular form of the system of equations, which is generated by the preprocessing step. Our method is able to check if the given system has a finite number of zeros and to compute verfied enclosures for all these zeros. Several test results demonstrate that our method is much faster than the application of Hansen’s multidimensional algorithm (or similar methods) to the original nonlinear systems of polynomial equations.