@article{AssagraAltafimdoCarmoetal.2020, author = {Assagra, Yuri A.O. and Altafim, Ruy Alberto Pisani and do Carmo, Joao P. and Altafim, Ruy A.C. and Rychkov, Dmitry and Wirges, Werner and Gerhard, Reimund}, title = {A new route to piezo-polymer transducers: 3D printing of polypropylene ferroelectrets}, series = {IEEE transactions on dielectrics and electrical insulation}, volume = {27}, journal = {IEEE transactions on dielectrics and electrical insulation}, number = {5}, publisher = {Inst. of Electr. and Electronics Engineers}, address = {Piscataway}, issn = {1070-9878}, doi = {10.1109/TDEI.2020.008461}, pages = {1668 -- 1674}, year = {2020}, abstract = {Here, a promising approach for producing piezo-polymer transducers in a one-step process is presented. Using 3D-printing technology and polypropylene (PP) filaments, we are able to print a two-layered film structure with regular cavities of precisely controlled size and shape. It is found that the 3D-printed samples exhibit piezoelectric coefficients up to 200 pC/N, similar to those of other PP ferroelectrets, and their temporal and thermal behavior is in good agreement with those known of PP ferroelectrets. The piezoelectric response strongly decreases for applied pressures above 20 kPa, as the pressure in the air-filled cavities strongly influences the overall elastic modulus of ferroelectrets.}, language = {en} } @article{AltafimBassoAltafimetal.2006, author = {Altafim, Ruy Alberto Pisani and Basso, Heitor Cury and Altafim, Ruy Alberto Pisani and Lima, L. and de Aquino, C. V. and Goncalves Neto, Luiz and Gerhard, Reimund}, title = {Piezoelectrets from thermo-formed bubble structures of fluoropolymer-electret films}, issn = {1070-9878}, doi = {10.1109/TDEI.2006.247822}, year = {2006}, abstract = {The acetone extracts of the root bark and stem bark of Erythrina sacleuxii showed antiplasmodial activities against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Chromatographic separation of the acetone extract of the root bark afforded a new isoflavone, 7-hydroxy-4 -methoxy-3'- prenylisoflavone (trivial name 5-deoxy-3' - prenylbiochanin A) along with known isoflavonoids as the antiplasmodial principles. Flavonoids and isoflavonoids isolated from the stem bark of E. sucleuxii were also tested and showed antiplasmodial activities. The structures were determined on the basis of spectroscopic evidence.}, language = {en} } @article{BassoAquinoAltafimetal.2006, author = {Basso, Heitor Cury and Aquino, C. V. and Altafim, Ruy Alberto Pisani and Altafim, Ruy Alberto Pisani and Gerhard, Reimund}, title = {Piezoelectricity of a single bubble formed by two oppositely charged Teflon-FEP films}, isbn = {1-4244-0547-5}, year = {2006}, language = {en} }