Standardization of Methods for Characterizing the Surface Geometry of Solids

Since a comprehensive survey published in 1999 [1] much work was done in standardizing measuring methods to characterize the surface geometry of dispersed and/or porous solids and to certify reference materials. The present paper is an extension of a short communication [2]. It gives a survey on existing standards and reports on new drafts and proposals.     

Deactivation reactions in the modeled 2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐mediated free‐radical polymerization of styrene: A comparative study with the 2,2,6,6‐tetramethyl‐1‐piperidinyloxy/acrylonitrile system

The competitiveness of the combination and disproportionation reactions between a 1‐phenylpropyl radical, standing for a growing polystyryl macroradical, and a 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) radical in the nitroxide‐mediated free‐radical polymerization of styrene was quantitatively evaluated by the study of the transition geometry and the potential energy profiles for the competing reactions with the use of quantum‐mechanical calculations at the density functional theory (DFT) UB3‐LYP/6‐311+G(3df, 2p)//(unrestricted) Austin Model 1 level of theory. The search for transition geometries resulted in six and two transition structures for the radical combination and disproportionation reactions, respectively. The former transition structures, mainly differing in the out‐of‐plane angle of the N? O bond in the transition structure TEMPO molecule, were correlated with the activation energy, which was determined to be in the range of 8.4–19.4 kcal mol^?1 from a single‐point calculation at the DFT UB3‐LYP/6‐311+G(3df, 2p)//unrestricted Austin Model 1 level. The calculated activation energy for the disproportionation reaction was less favorable by a value of more than 30 kcal mol^?1 in comparison with that for the combination reaction. The approximate barrier difference for the TEMPO addition and disproportionation reaction was slightly smaller for the styrene polymerization system than for the acrylonitrile polymerization system, thus indicating that a β‐proton abstraction through a TEMPO radical from the polymer backbone could diminish control over the radical polymerization of styrene with the nitroxide even more than in the latter system. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 232–241, 2007     

How much sweetness is there in the universe?

We continue investigations of forcing notions with strong ccc properties introducing new methods of building sweet forcing notions. We also show that quotients of topologically sweet forcing notions over Cohen reals are topologically sweet while the quotients over random reals do not have to be such. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Multipeak distributions of first passage times in bistable dynamics in a model of a thermochemical system.

A master equation is used to study transitions between the stable limit cycle and stable focus in the two-variable bistable system. The distribution function of the mean first passage time between these attractors and the relative dispersion of the mean first return time from the stable focus to itself as a function of the intensity of fluctuations are calculated and discussed. A coherence resonance is observed for the return time from the focus to itself.     

Coupled Hartree-Fock calculation of the H-bond chemical shift in FHF

A coupled Hartree-Fock calculation of the proton shielding constant in FHF⁻ with a reasonably good basis set of contracted gaussian orbitals leads to an extremely large upfield H-bond chemical shift with respect to the HF molecule. An approximate scheme, based on the requirement of the gauge origin independence of the finite basis set coupled Hartree-Fock calculations of the magnetic susceptibility, provides a considerable improvement of the computed proton shielding constant and results in the required downfield H-bond chemical shift of the proton resonance. The computed H-bond shift for FHF⁻ agrees with the experimental data.     

Use of carbon suboxide to obtain block and graft copolymers. I. Grafting of carbon suboxide on polyamide 6

Polyamide 6 in the form of film was grafted by gaseous carbon suboxide in the form of toluene solutions. The influence of temperature on the extent of grafting was studied. It was concluded that in a sufficiently high temperature a copolymer of high structure appears. The influence of substances that initiate homopolymerization of suboxide upon the course of grafting reaction was studied. It was found that the substances do not increase the effectiveness of grafting. However a significant increase of effectiveness of grafting is produced by introducing into the reaction environment some small quantities of methanol. By the addition of methanol a graft copolymer of a maximum effectiveness of 43.1% was obtained. The copolymer was subjected to further tests and appeared to be c.l. poly(amide-6–g-carbon suboxide). Additional tests indicated that the polyamide film graft with carbon suboxide shows some interesting properties.     

High temperature crystallization of aluminum fluoride. Course,hydrolysis, solid phases.

A study for AlF₃ crystallization from water solution was performed in the temperature range 100 to 200°C.Four solid phases were found to be precipitated, AlF₃.3H₂O (up to ca.120°C, cubic α-AlF₃.H₂O (decomposition of AlF₃.3H₂O in suspension), hexagonal β -AlF₃.H₂O (direct from solution) and the hydroxyfluoride Al(OH,F)₃.H₂O with an F/Al ratio of ca. 2.5 (hydrolysis of AlF₃). The extent of hydrolysis was established as a function of the initial AlF₃ concentration.X-ray diffraction and thermogravimetric data for the monohydrates were given and differences between the two indicated.     

Potentiometrische Bestimmung von Seltenen Erden (z. B. Erbium)

Zusammenfassung Eine schnelle und zuverlässige, potentiometrische Titrationsmethode zur Bestimmung von Erbium mit Ammoniumoxalatlösung in wäßrig-acetonischem Medium im Verhältnis 11 wurde ausgearbeitet. Man titriert in dem System Pt | ErCl₃ | Hg₂Cl₂ + KCl | Hg. Der Potentialsprung im Äquivalenzsättigungspunkt ist bereits auf Zugabe eines Tropfens Reagenslösung sehr deutlich. Der Meßfehler überschreitet nicht die Grenzen ±0,5%.Die Methode ist bei Metallionen, die mit Ammoniumoxalat schwerlösliche Niederschläge bilden, nicht anwendbar.

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Summary A rapid and accurate method for the potentiometric titration of erbium by means of ammonium oxalate solution in a water-acetone medium (11) has been worked out. The system Pt | ErCl₃ | Hg₂Cl₂ + KCl | Hg was used. The potential jump at the neutral point is distinct, even if only one drop of the reagent is added. The error of the measurement is not greater than ±0,5%- Metal ions forming insoluble precipitates with ammonium oxalate interfere with this method.

     

An investigation of the reliability of the Galerkin-Petrov method

It is shown that the Galerkin-Petrov method if applied in a controlled way yields reliable results for excited states of the same symmetry classifications as the ground state. Computations are performed for the 2¹ S and 3¹ S states of He. The problem of optimizing nonlinear parameters of the basis functions by means of the GP method is discussed. A special optimization scheme is suggested and numerically illustrated for someS states of He.     

The use of bathoferroine for extraction-spectrophotometric determinations of microamounts of perchlorate and perrhenate

Bathoferroine can be used for anion determinations by a method based on selective ion-pair extraction if the selectivity of extraction has been enhanced by addition of nonelectrolyte to the water phase. The method of perchlorate and perrhenate determinations characterizes parameters similar to those obtained by methods in which other cation complexes have been used. The advantage of the proposed method is the possibility of considerable concentration of ion association compound extracts by nitromethane reextraction.