The thermodynamic dissociation constant of naphazoline by the regression analysis of potentiometric data

The mixed dissociation constant of naphazoline is determined at various ionic strengths I [mol dm⁻³] in the range of 0.01 to 0.26 and at temperatures of 25°C and 37°C using ESAB and HYPERQUAD regression analysis of the potentiometric titration data. A strategy of efficient experimentation is proposed in a protonation constant determination, followed by a computational strategy for the chemical model with a protonation constant determination. Two group parameters, L ₀ and H _T were ill-conditioned in the model and their determination is therefore uncertain. These group parameters, L ₀ and H _T, can significantly influence a systematic error in the estimated common parameter pK_a and they always should be refined together with pK _a. The thermodynamic dissociation constant pK _a^T was estimated by nonlinear regression of {pK _a, I} data at 25°C and 37°C: for naphazoline pK _al^T = 10.41(1) and 10.13(2). Goodness-of-fit tests for various regression diagnostics enabled the reliability of the parameter estimates to be found.      

Finite retracts of Priestley spaces and sectional coproductivity

Let Y and P be posets, let P be finite and connected, and let f : Y → P be a surjective monotone map. The map f can be naturally extended to a Priestley surjection ${\widehat{f} : \widehat{Y} \to P}$ which can turn out to be a retraction even if f is not. We characterize those maps f whose Priestley extensions ${\widehat{f}}$ are retractions. We then use this characterization to contrast, yet again, the behavior of cyclic and acyclic posets P insofar as their appearances in Priestley spaces are concerned. We say that P is sectionally coproductive if the Priestley surjection ${f : {\coprod} X_{i} \to P}$ , induced by Priestley surjections f _i : X _i → P, is a retraction only when at least one of the f _i ’s is a retraction. We then prove that P is sectionally coproductive exactly when it is acyclic.     

Code loops in both parities

We present equivalent definitions of code loops in any characteristic p≠0. The most natural definition is via combinatorial polarization, but we also show how to realize code loops by linear codes and as a class of symplectic conjugacy closed loops. For p odd, it is possible to define code loops via characteristic trilinear forms. Related concepts are discussed.     

Effect of protonation exothermicity on the chemical ionization mass spectra of some alkylbenzenes

The H₂, N₂/H₂, CO₂/H₂, N₂O/H₂, CO/H₂ and CH₄ chemical ionization mass spectra of thirteen C₈ to C₁₁ alkylbenzenes are reported. Characteristic hydride and alkide ion abstraction reactions are observed with all reagent gases. The major fragmentation reactions of [MH]⁺ are olefin elimination to form a protonated arene and arene elimination to form an alkyl ion. From the effect of structure and protonation exothermicity it is concluded that rearrangement of primary alkyl groups to the more stable secondary or tertiary structure occurs prior to alkyl ion formation. A detailed fragmentation mechanism for protonated arenes is proposed. The ‘effective’ proton affinity of the methane-derived reagent system is estimated to be ～556 kJ mol^?1.     

A difference between continuous and absolutely continuous norms in Banach function spaces

On examples we show a difference between a continuous and absolutely continuous norm in Banach function spaces.     

Einige neue Erkenntnisse über die Degradation von Titanaten im Zusammenhang mit der Exoemission

Ohne Zusammenfassung

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