Monitoring of the Proton Electrochemical Gradient in Reconstituted Vesicles: Quantitative Measurements of Both Transmembrane Potential and Intravesicular pH by Ratiometric Fluorescent Probes

Proteoliposomes carrying reconstituted yeast plasma membrane H⁺-ATPase in their lipid membrane or plasma membrane vesicles are model systems convenient for studying basic electrochemical processes involved in formation of the proton electrochemical gradient (Δμ_H ⁺) across the microbial or plant cell membrane. Δψ- and pH-sensitive fluorescent probes were used to monitor the gradients formed between inner and outer volume of the reconstituted vesicles. The Δψ-sensitive fluorescent ratiometric probe oxonol VI is suitable for quantitative measurements of inside-positive Δψ generated by the reconstituted H⁺-ATPase. Its Δψ response can be calibrated by the K⁺/valinomycin method and ratiometric mode of fluorescence measurements reduces undesirable artefacts. In situ pH-sensitive fluorescent probe pyranine was used for quantitative measurements of pH inside the proteoliposomes. Calibration of pH-sensitive fluorescence response of pyranine entrapped inside proteoliposomes was performed with several ionophores combined in order to deplete the gradients passively formed across the membrane. Presented model system offers a suitable tool for simultaneous monitoring of both components of the proton electrochemical gradient, Δψ and ΔpH. This approach should help in further understanding how their formation is interconnected on biomembranes and even how transport of other ions is combined to it.     

CO2-laser photoacoustic detection of gaseous n-pentylacetate

The absorption spectra of gaseous n-pentylacetate were investigated by FT IR spectroscopy as well as CO₂-laser photoacoustic spectroscopy for simulation of the dispersion of a nerve agent (sarin) within a modeled atmospheric boundary layer. Three CO₂-laser emission lines were used for photoacoustic detection of n-pentylacetate with detection limit in the range of 1-3 ppm.     

Linearly polarized, 3.35 W narrow-linewidth, 1150 nm fiber master oscillator power amplifier for frequency doubling to the yellow

A high-power linearly polarized Yb-doped silica fiber master oscillator power amplifier at 1150 nm is reported. It produced 3.35 W cw and 2.33 W of average power in 1 micros pulses at a 100 kHz repetition rate, both with 8 pm linewidth. This is the first report, to the best of our knowledge, of a high-power Yb-doped fiber amplifier at a wavelength longer than 1135 nm. The pulsed output was frequency doubled in a bulk periodically poled near-stoichiometric LiTaO(3) chip to generate 976 mW of average power at 575 nm with an overall system optical-to-optical efficiency of 9.8% with respect to launched pump power.     

On the stereochemistry of photoaddition between α,β-unsaturated ketones and olefins. III.

The α,β-unsaturated ketone $\text{1}$ yields with allene the photocycloadduct $\text{3}$ predicted by our empirical photoaddition rule and the byproduct 7. The formation of this material may be rationalized by the sequence $\text{1}$ → $\text{4}$ → $\text{5}$ → $\text{6}$ → $\text{7}$. The isomeric ketone $\text{2}$ is unreactive under the same conditions, since α addition is prohibited by the rule and β addition is severely blocked.     

Determination of some pharmaceuticals using simple potentiometric sensors of coated-wire type

Summary The preparation of simple potentiometric sensors of the coated-wire type is described and working instructions for their use are given. The sensors prepared from an ordinary aluminium conductor, being simple and cheap, can well serve to monitore the titrations based on ion-pair formation. The application possibilities are discussed and shown as practical examples on analyses of nasal and eye drops containing cationic surfactants or salts of alkaloids.

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Bestimmung einiger Arzneimittel mit Hilfe einfacher potentiometrischer Sensoren

Zusammenfassung Die Herstellung einfacher potentiometrischer Sensoren mit isoliertem Draht und deren Verwendung wurde beschrieben. Aus einfachem Aluminiumdraht sind sie billig und können für Titrationen auf der Grundlage von Ionenpaar-Bildung dienen. Die Möglichkeiten ihrer Anwendung wurden erörtert und praktiziert für die Untersuchung von Nasen- und Augentropfen mit kationischen Schaumbildnern oder von Alkaloidsalzen.

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According to the Poster XII-23 presented at Euroanalysis V, Cracow, August 1984; the comments inserted into the text are a consequence of the discussion.     

Synthesis and NMR characterization of the cis and trans isomers of [Pt(II)(N9-adeH)2(pz)2] and X-ray crystallography of the trans isomer

The reaction of tetrapyrazine Pt(II) with adenine under basic conditions yielded two products both disubstituted by adenine and bound in all cases to the N-9 nitrogen of adenine. Crystals amenable to X-crystallographic analysis were obtained for one product which was consequently identified as trans-[Pt(II)(N9-adeH)2(pz)2](NO3)(4).H2O. The other product, though, was identified as the cis isomer based on extensive and comparative NMR structural studies whereby the two compounds were examined as both neutral and tetraprotonated species in solution. The major product of the reaction was unexpectedly the cis isomer, thus obtained in contrast to the trans effect, and the reason for this result is speculated on. Computational calculations using DFT at the B3LYP/TZVP-MARI-J level of theory provided the head-to-tail conformer as the overwhelmingly more stable species over the head-to-head conformer for both compounds whilst the trans product was found to be more stable than the cis. Thus the reaction does not follow a thermodynamic course and rather is kinetically controlled in concert with the speculated mode of reaction.     

Numerical Analysis of the Rebellious Voter Model

The rebellious voter model, introduced by Sturm and Swart (2008), is a variation of the standard, one-dimensional voter model, in which types that are locally in the minority have an advantage. It is related, both through duality and through the evolution of its interfaces, to a system of branching annihilating random walks that is believed to belong to the ‘parity-conservation’ universality class. This paper presents numerical data for the rebellious voter model and for a closely related one-sided version of the model. Both models appear to exhibit a phase transition between noncoexistence and coexistence as the advantage for minority types is increased. For the one-sided model (but not for the original, two-sided rebellious voter model), it appears that the critical point is exactly a half and two important functions of the process are given by simple, explicit formulas, a fact for which we have no explanation.