The c-axis critical current density J(c)(c) has been recently found to be orders of magnitude lower than the ab-plane critical current density J(c)(ab). Here we report on J(c)(c) (77 K, sf) values of various YBa2Cu3O7-based (YBCO) tapes with different microstructures. Our results show that the value of J(c)(c) (77 K, sf) decreases significantly with increasing concentration of ab-plane stacking faults in YBCO thin films and that the critical current anisotropy gamma = J(c)(ab)/J(c)(c)
can reach values as high as 2070, implying that in the highest-anisotropy tape, similar to 20% of the tape width carries c-axis current in a helically wound power cable. VC 2011 American Institute of Physics. [doi:10.1063/1.3653292]“
“Polyurethanes with multiblock copolymers of poly(?-caprolactone) (PCL) and poly(tetramethylene ALK inhibitor drugs oxide) glycol (PTMG) or poly(ethylene glycol) (PEG) as a soft segment were synthesized in situ via reactive extrusion from ?-caprolactone (CL) and 4,4′-diphenylmethane
diisocyanate https://www.selleckchem.com/products/pifithrin-alpha.html (MDI). The titanium alkoxide mixture generated from an ester-exchange reaction between titanium propoxide [Ti(OPr)4], and excessive PTMG or PEG was used as an initiator and catalyst. Compared to the reported fabrication of polycaprolactone-based polyurethane (PCLU), the in situ reactive extrusion preparation not only explored a new rapid route for the fabrication of PCLU but also offered a simplified, controllable approach for the production of PCLU in a successive mass scale. A series of PTMGPCLUs and PEGPCLUs with different PCL block-average degrees of polymerization (DPn’s) were prepared by only an adjustment of the relative concentration of CL in the reaction system, with a certain constant molar ratio of MDI to titanium alkoxide. 1H-NMR, gel permeation chromatography, and differential scanning calorimetry results indicate that all of the CL monomers were converted in the polymerization, and the molecular weight of the copolymers was
about 8 x 10(4) g/mol with a polydispersity index of approximate 2.4. With an increase in the PCL block-average DPn in PTMGPCLU from 25 to 40, the tensile selleck chemicals llc strength increased from 16.5 to 22.7 MPa, and the melting point increased from 46.1 to 49.5 degrees C. It was also verified by PEGPCLU prepared with organic Ti of lowered content in the initiator mixture that the mechanical properties could be greatly affected and dropped with decreasing content of organic Ti in the initiator mixture. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012″
“We propose that the cognitive mechanisms that enable the transmission of cultural knowledge by communication between individuals constitute a system of ‘natural pedagogy’ in humans, and represent an evolutionary adaptation along the hominin lineage. We discuss three kinds of arguments that support this hypothesis.