Civil Engineering Education and Complex Systems

Civil engineering is an interdisciplinary field, and most of the projects designed and built represent very complex systems, both during the construction phase and in the built phase. This research describes how a course in land development that included engineering design elements, lectures that also touched on other related fields, and a field journal assignment at a “green” (sustainable) construction site facilitated students’ understanding of complex systems. Results suggest that this course design facilitates the development of students’ proficiencies in several skill sets, and can increase students’ understanding of the complexity involved in civil engineering projects.     

Complementary techniques for the characterization of thin film Ti/Nb multilayers

An aberration corrector on the probe-forming lens of a scanning TEM (STEM) equipped with an electron energy-loss spectrometer (EELS) and X-ray energy-dispersive spectrometer (XEDS) has been employed to investigate the compositional variations as a function of length scale in nanoscale Ti/Nb metallic multilayers. The composition profiles of EELS and XEDS were compared with the profiles obtained from the complementary technique of 3D atom probe tomography. At large layer widths (h≥7 nm, where h is the layer width) of Ti and Nb, XEDS composition profiles of Ti/Nb metallic multilayers are in good agreement with the EELS results. However, at reduced layer widths (h≈2 nm), profiles of EELS and atom probe exhibited similar compositional variations, whereas XEDS results have shown a marked difference. This difference in the composition profiling of the layers has been addressed with reference to the effects of beam broadening and the origin of the signals collected in these techniques. The advantage of using EELS over XEDS for these nanoscaled multilayered materials is demonstrated.     

Investigation of the cationic distribution within the lattice of a series of niobates with tetragonal tungsten bronze structure

Single Crystals of the series K₃Sr₂LnNb₁₀O₃₀ (Ln?=?Lanthanide) have been grown by two different techniques: micro-pulling down and solid state growth. The cationic distribution within the three large cavities of the lattice, determined from the crystal structure resolution, shows that the crystal-chemical formula is depending on the route of preparation. A spectroscopic study has evidenced a broadening of the emission peaks which is also compatible with a disorder distribution of Ln³⁺ ions over 12- and 15-fold cavities.     

EXTRACTION OF TRANSITION METALS FROM WOOD PULP FIBERS USING SUPERCRITICAL CARBON DIOXIDE

The supercritical fluid extraction of manganese and iron from solid matrix (wood pulp) is demonstrated experimentally. Supercritical carbon diodixe is used together with lithium bis(trifluoroethyl) dithiocarbonate (FDDC) as the ion-pairing reagent. The metal content of the pulp samples was determined by inductively couple plasma atomic emission spectroscopy (ICP-AES). Optimum conditions were determined to be 30 min each of static and dynamic extraction with 200 atm pressure at 40 °C. Thermomechanical pulp (TMP) extracted under these parameters exhibits an 80% decrease in manganese content, and 91% after a second, sequential extraction. The simultaneous removal of iron was found to be only 6% and supports evidence that it is much more strongly bound to the TMP matrix than manganese.     

Design and Expected Performance of GISMO-2, a Two Color Millimeter Camera for the IRAM 30 m Telescope

We present the main design features for the GISMO-2 bolometer camera, which we build for background-limited operation at the IRAM 30 m telescope on Pico Veleta, Spain. GISMO-2 will operate simultaneously in the 1 and 2 mm atmospherical windows. The 1 mm channel uses a \(32 \times 40\) TES-based backshort under grid (BUG) bolometer array, the 2 mm channel operates with a \(16 \times 16\) BUG array. The camera utilizes almost the entire full field of view provided by the telescope. The optical design of GISMO-2 was strongly influenced by our experience with the GISMO 2 mm bolometer camera, which is successfully operating at the 30 m telescope. GISMO is accessible to the astronomical community through the regular IRAM call for proposals.     

Arylidene polymers XIX: Synthesis and properties of aromatic polyphosphate from diarylidenecycloalkanones

Polyphosphate esters were synthesized by interfacial polymerization of 2,5-bis(p-hydroxybenzylidene)cyclopentanone, 2,5-divanillylidenecyclopentanone, 2,6-bis(p-hydroxybenzylidene)cyclohexanone, 2,6-divanillylidenecyclohexanone or 2,7-bis(p-hydroxybenzylidene)cycloheptanone with phenyl phosphorodichloridate. The resulting polymers were characterized by elemental analysis, IR spectroscopy, solubility and viscometry measurements. The thermal properties of the polymers were evaluated by TGA measurements and correlated with their structural units. The crystallinity of all the polyphosphate esters was tested by X-ray analysis.