Functionalized oligo-ɛ-caprolactones synthesized by heterogeneous coordinated anionic ring opening polymerization (AROP) in protic conditions have been analyzed by mass spectrometry in order to ...investigate the molecular weight distribution as well as the possible occurrence of macrocycles.Mass spectra obtained from LSIMS revealed the presence of fragmentation products and some of them have been identified. Macrocycles were also detected. Nevertheless, ESI and MALDI-TOF spectrometries do not confirm the presence of macrocycles in the samples. The same results have been obtained by analysis of commercially available polycaprolactones.
We demonstrate 6.4 Tb/s WDM transmission based on the phase-shaped binary transmission scheme and strong optical filtering over 2,100 km, yielding a record 13.3 Pbit/smiddotkm capacity times distance ...for terrestrial systems. A particularly good tolerance to non-linearities at 40 Gb/s has been measured
A variety of nonionic reactive surfactants have been prepared from block copolymer precursors. These precursors are formed from a commercially available polyoxyethylene glycol monomethylether as the ...hydrophilic sequence of the surfactant; this product is used as initiator of ring opening anionic polymerization of butylene oxide. Finally the reactive surfactants are obtained after proper functionalization of the precursor. The reactive surfactants are an inisurf with an asymmetric azo compound, a transurf with a thiol group, and a few surfmers with acrylic, methacrylic, styrenic and α-methyl styrenic reactive groups. These compounds have been engaged in styrene emulsion or dispersion polymerization. Several of them have been found to be useful for preparing stable latices.PUBLICATION ABSTRACT
The energetics of alpha-aminoisobutyric acid transport were examined in Vibrio costicola grown in a medium containing the NaCl content (1 M) optimal for growth. Respiration rate, the membrane ...potential (delta psi) and alpha-aminoisobutyric acid transport had similar pH profiles, with optima at 8.5-9.0. Cells specifically required Na+ ions to transport alpha-aminoisobutyric acid and to maintain the highest delta psi (150-160 mV). Sodium was not required to sustain high rates of O2-uptake. Delta psi (and alpha-aminoisobutyric acid transport) recovered fully upon addition of Na+ to Na+-deficient cells, showing that Na+ is required in formation or maintenance of the transmembrane gradients of ions. Inhibitions by protonophores, monensin, nigericin and respiratory inhibitors revealed a close correlation between the magnitudes of delta psi and alpha-aminoisobutyric acid transport. Also, dissipation of delta psi with triphenylmethylphosphonium cation abolished alpha-aminoisobutyric acid transport without affecting respiration greatly. On the other hand, alcohols which stimulated respiration showed corresponding increases in alpha-aminoisobutyric acid transport, without affecting delta psi. Similarly, N,N'-dicyclohexylcarbodiimide (10 microM) stimulated respiration and alpha-aminoisobutyric acid transport and did ot affect delta psi, but caused a dramatic decline in intracellular ATP content. From these, and results obtained with artificially established energy sources (delta psi and Na+ chemical potential), we conclude that delta psi is obligatory for alpha-aminoisobutyric acid transport, and that for maximum rates of transport an Na+ gradient is also required.
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