The anhydride structure of several previously reported stable areneselenenic acids1

The compounds previously reported² to be the stable areneselenenic acids, $\text{o}$-nitro-($\text{la}$ and $\text{+o}$-benzoylbenzeneselenenic acid ($\text{lb}$), are shown actually to be the corresponding selenenic anhydrides (ArSeOSeAr). Solutions of the selenenic acids (ArSeOH), however, can be easily generated from the anhydrides byacid-catalyzed hydrolysis.     

Thermal decomposition of PTFE in the presence of silicon,calcium silicide,ferrosilicon and iron

Simultaneous TG/DTA has been used to study the thermal decomposition of binary compositions containing polytetrafluoroethene (PTFE) with silicon (Si), calcium silicide (CaSi₂), ferrosilicon (FeSi) or iron (Fe) powders. In nitrogen and under dynamic heating program the thermal decomposition of Si/PTFE and CaSi₂/PTFE is an exothermic process. The other two compositions decompose endothermically. In each case the decomposition reactions show first-order kinetics but only iron does not change considerably the kinetics of PTFE depolymerization. The constants of the decomposition rate at 850 K for silicon containing reducers are about four times higher than those of PTFE and Fe/PTFE. This revised version was published online in July 2006 with corrections to the Cover Date.     

The mass spectra of halogeno derivatives of quinoxaline

The mass spectra of seventeen different quinoxaline halogeno derivatives are reported. The fragmentation mechanism is discussed.     

On meromorphic univalent functions omitting a disc

The class Σ_b is defined to consist of meromorphic univalent functionsH omitting a disc with the radiusb:H(z)=z+ Σ ₀ ^∞ A _n z ⁻ⁿ ,z>1,H(b)>b ∈ (0, 1). By aid of FitzGerald inequalities the inverse coefficients of odd Σ_b-functions are maximized. The result extends the corresponding estimation, due to Netanyahu and Schober, fromb=0 to the whole interval (0, 1). The author wishes to express her gratitude to Professor O. Tammi for valuable discussions connected with the problem. This work was supported by a grant from the Finnish Ministry of Education.     

Determination of boron in copper and copper-, nickel- and cobalt-base alloys

Summary A pyrohydrolytic method for the extraction of boron from coppper and copper-, nickel- and cobalt-base alloys has been developed. For concentrations higher than 0.1 %, boron is determined by an alkalimetric method in the presence of mannitol and phenolphthalein or by a potentiometric method. For samples containing less than 0.1% of boron, it is determined by spectrophotometry with azomethine H. Standard deviations are in the range of 0.008 to 0.15% B.

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Bestimmung von Bor in Kupfer sowie Legierungen auf Kupfer-, Nickel- und Kobaltbasis

Zusammenfassung Zur Extraktion von Bor aus diesen Proben wurde ein pyrohydrolytisches Verfahren ausgearbeitet. Die Borbestimmung erfolgt bei Gehalten >0,1% B alkalimetrisch in Gegenwart von Mannit und Phenolphthalein oder potentiometrisch, bei Gehalten <0,1% B durch Spektralphotometrie mit Azomethin H. Die Standardabweichungen liegen im Bereich von 0,008–0,15% B.

     

The Structure of Water-Swollen Poly(Vinyl Alcohol) and the Swelling Mechanism

The swelling mechanism of poly(vinyl alcohol) (PVA) in a wide range of the equilibrium swelling index, of 7–153% (with H₂O) and of 12-297% (with D₂O), was investigated by IR, Raman, and broad-band NMR spectroscopy. Analysis of the spectral data obtained confirmed the presence of hydration water (bonded with polymer-free hydroxyl groups) and condensation water (not having been bonded with polymer hydroxyl groups) in poly(vinyl alcohol) swollen samples at low (～7%) and high (>23%) equilibrium swelling indexes, respectively. Moreover, it revealed the intra- and inter-molecular hydrogen bonds breaking in the polymer swollen to higher extent (equilibrium swelling index > 85%).