Voltammetric study of the ph-behaviour of acetylacetone at the lead dioxide electrode in aqueous solutions

Summary The electrode reaction of acetylacetone (AA) was investigated in unbuffered aqueous solutions by using 3 lead dioxide (PbO₂) indicator electrode. A pH-range of about 2 to 12 was covered. At a pH higher than 3 and lower than 9, the height of the anodic and cathodic peaks is directly proportional to the AA concentration. The PbO₂ electrode seems to be useful for determining a complexing agent such as AA.

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Voltammetrische Untersuchung des pH-Verhaltens Acetylaceton in wäßriger Lösung an der Bleidioxid-Elektrode

Zusammenfassung Die Elektrodenreaktion von Acetylaceton wurde in ungepufferten wäßrigen Lösungen an der PbO₂-Indicatorelektrode untersucht, wobei ein pH-Bereich von 2 bis 12 erfaßt wurde. Bei pH-Werten > 3 und < 9 ist die Höhe der anodischen und kathodischen Peaks direkt proportional der Acetylacetonkonzentration. Die PbO₂-Elektrode scheint für die Bestimmung von Komplexbildnern (wie Acetylaceton) nützlich zu sein.

     

Photon number squeezing of ultrabroadband laser pulses generated by microstructure fibers

To the best of our knowledge, we demonstrate for the first time the generation of photon number squeezing by spectral filtering for ultrabroadband light generated by microstructure fibers at 800 nm. A maximum squeezing of 4.6 dB is observed, corresponding to 10.3 dB after correcting for detection losses. We numerically analyzed the quantum dynamics of ultrashort laser pulse propagation through optical fibers by solving a nonlinear quantum Schr?dinger equation that included Raman scattering, especially for the quantum correlation of photon number fluctuation among frequency modes in broadband pulses.     

Novel stereoselective entry to 2'-beta-carbon-substituted 2'-deoxy-4'-thionucleosides from 4-thiofuranoid glycals

2'-Beta-methyl- and 2'-beta-hydroxymethyl-2'-deoxy-4'-thionucleosides have been synthesized through PhSeCl-mediated electrophilic glycosidation using 4-thiofuranoid glycals having carbon substituents at the C2-position as a glycosyl donor. Preparation of these glycals were carried out by means of the C2 lithiation of 1-chloro-4-thiofuranoid glycal with LTMP followed by the Birch reduction of the chlorine atom. [reaction: see text]     

Human hand moves proactively to the external stimulus: an evolutional strategy for minimizing transient error

We investigated particularly the proactive nature of the visual-motor system by steady and transient experiments of a hand-tracking task, and confirmed that the hand motion precedes on the average the target motion in steady runs within a finite frequency range of the sinusoidal target motion. The question why and how much the hand motion should precede was answered by frequency-jump experiments. The results implied that the positive phase shift of the hand motion represents the proactive nature of the visual-motor control system which is adaptationally developed for each person to minimize the transient error of the hand motion when the target motion changes unexpectedly.     

Efficient 355-nm generation in CsB3O5 crystal

We demonstrate UV generation in CSB3O5 (CBO) crystals grown by the top-seeded solution growth technique. 355-nm UV light was generated by use of a type II CBO crystal as a sum frequency of the fundamental light and the second harmonic of a nanosecond Nd:YVO4 laser. A 3.0-W output of the third-harmonic was obtained at a repetition rate of 31 kHz. The conversion efficiency from the fundamental light to the third harmonic reached 30%, which was 1.5 times higher than that obtained with a type II LiB3O5 crystal under the same experimental conditions.     

Beam-polarization asymmetries for the p(gamma-->, K+)Lambda and p(gamma-->, K+)Sigma(0) reactions for E(gamma)=1.5-2.4 GeV

Beam polarization asymmetries for the p(gamma-->,K+)Lambda and p(gamma-->,K+)Sigma(0) reactions are measured for the first time for E(gamma)=1.5-2.4 GeV and 0.6相似文献   

Novel fluorescent isoquinoline pigments, panaefluorolines A-C from the cultured mycobiont of a lichen, Amygdalaria panaeola

Novel fluorescent substances, named panaefluorolines A-C (1-3), were isolated from the cultured mycobiont of a lichen, Amygdalaria panaeola. These structures were elucidated on the basis of spectroscopic data, especially 2D NMR.