Lead Zirconate-Titanate Films Prepared from Soluble Powders

Precursor powders for Pb(Zr1 – xTix) O3 (PZT) thin films were produced by the reaction of zirconium-and titanium-n-propoxides with acetylacetone and lead acetate trihydrate. The subsequent complete removal of volatile components yielded powders that can be handled in air. The powders are indefinitely stable under ambient conditions.High molarity (>2m) coating sols were prepared by dissolution of the precursor powders in mixtures of 1,3-propanediol, triethanolamine (TEA) and water. Excess amounts of lead to compensate lead loss during firing were easily introduced into these solutions.The deposition of these sols on steel substrates and firing at 600°C yielded PZT films. Many physical parameters like film thickness, morphology and electrical performance could be influenced by choice of the solvent mixture composition and oxide content of the sols. Depending on the preparation dielectric permittivities, r of up to 840 were measured at 1 kHz. By hysteresis measurements at 50 Hz and a field amplitude of 50 V/m a remanent polarization of about 40 C/cm2 and coercivity of about 8 V/m was obtained. The films were stable against dielectric breakdown up to 70V/m.     

Nanomotors

This minireview discusses whether catalytically active macromolecules and abiotic nanocolloids, that are smaller than motile bacteria, can self-propel. Kinematic reversibility at low Reynolds number demands that self-propelling colloids must break symmetry. Methods that permit the synthesis and fabrication of Janus nanocolloids are therefore briefly surveyed, as well as means that permit the analysis of the nanocolloids’ motion. Finally, recent work is reviewed which shows that nanoagents are small enough to penetrate the complex inhomogeneous polymeric network of biological fluids and gels, which exhibit diverse rheological behaviors.     

Transcranial stimulability of phosphenes by long lightning electromagnetic pulses

The electromagnetic pulses of rare long (order of seconds) repetitive lightning discharges near strike point (order of 100 m) are analyzed and compared to magnetic fields applied in standard clinical transcranial magnetic stimulation (TMS) practice. It is shown that the time-varying lightning magnetic fields and locally induced electric fields are in the same order of magnitude and frequency as those established in TMS experiments to study stimulated perception phenomena, like magnetophosphenes. Lightning electromagnetic pulse induced transcranial magnetic stimulation of phosphenes in the visual cortex is concluded to be a plausible interpretation of a large class of reports on luminous perceptions during thunderstorms.     

Development of DSM's hybrane® hyperbranched polyesteramides

The development of DSM's Hybrane® hyperbranched poly(ester amides) is described. The monomer (1) for the hyperbranched polyester is obtained from the reaction of a cyclic anhydride with diisopropanol amine, yielding a tertiairy amide with one COOH and two OH groups. Polycondensation takes place via an oxazolinium intermediate in bulk at relatively mild conditions in the absence of catalyst. The reaction has been scaled up to ton scale. By varying and combining anhydrides, and modification with several types of end groups, a large variety of structures with concomitant properties and industrial applications has been realized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3110–3115, 2004     

Reductive dimerization of dithianylium salts and fluorodesulfuration: a new synthetic approach to tetrafluoroethylene substructures

The reductive dimerization of dithianylium ions, followed by oxidative fluorodesulfuration, opens a convenient access to a variety of 1,2-disubstituted tetrafluoroethylene derivatives. A similar method leads to hexafluorodiacetyl, a potential building block for fluorinated heterocycles.     

Synthesis of an L-Fucose-Derived Cyclic Nitrone and its Conversion to α-L-Fucosidase Inhibitors

The L -fuco-nitrone 1 has been synthesized from allyl 4,6-O-benzylidene-α-D -glucopyranoside ( 4 ) in 11 steps and an overall yield of 18%. The key step is the intramolecular alkylation of an intermediary 1,1-bis(hydroxylamine) derived from the tosyloxy oximes (E/Z)- 2 . The nitrone 1 has been transformed into the diamine 30 , the indolizidines 39 and 40 , the indolizidinones 34 and 35 , and the imidazole 44 , all inhibiting bovine epididymis α-L -fucosidase with IC₅₀ values between 105 nM and 240 μM .