Search results for "CONSTANT"

Preparation and Investigation of BaSO4KMnO4 Crystals

1969

BaSO4 crystals containing KMnO4 prepared by precipitation were investigated morphologically, chemically and by X-ray diffraction. The colour of the preparations is homogeneous and stable. The colour intensity and also the amount of dissolved KMnO4 (maximum approx. 30 Mol%) increases with concentration of KMnO4 in the reaction solution to a limiting value dependent on the temperature. The lattice constants or the unit cell volume of the BaSO4–KMnO4 crystals increase with the proportion of KMnO4. The experimental values agree well with the Vegard rule for preparations up to 18 Mol% KMnO4, but with higher proportions significant departures were observed. They may easily be explained by adsorpt…

Kinetic study of the oxidation of [Fe(CN)6]4− by [Co(NH3)4pzCO2]2+ and S2O82- in the presence of the tripodal ligand Tren Aminopropil

2011

Abstract Oxidations (electron transfers) of [Fe(CN)6]4− by [Co(NH3)4pzCO2]2+ and S 2 O 8 2 - have been studied in solutions containing the receptor N,N′,N″-(aminopropil)-tris (2-aminoetil) amina [Tren Aminopropil, TAL], which can incorporate [Fe(CN)6]4− and S 2 O 8 2 - but not the cobalt complex. The results can be explained using the Bronsted equation that allows to obtain the binding constant of the transition state, a parameter that the Pseudophase Model cannot provide.

The essential identity of the framework structures of ZSM-8 and ZSM-5

1994

The crystal structures of TEA-ZSM-8 and its calcined template-free form have been studied by Rietveld analyses based on X-ray powder diffraction data. The results show that the aluminosilicate framework structure of ZSM-8 is essentially identical to that of ZSM-5. The tetraethylammonium molecule could be located in the difference Fourier analysis yielding positions similar to its TPA counterpart in ZSM-5. Lattice constants of ZSM-8 are in the same range as for ZSM-5. Contrary results are related to incorrectly indexed powder patterns. Optical investigations of ZSM-5 and ZSM-8 crystals showed that the zeolites studied here are both twinned exhibiting differently shaped twin individuals.

“El Todo Poderoso nos ayude, para llegar a lo que deseamos”: homosexuality and Catholicism in Franco’s Spain (1954–1970)

2021

This article traces the constant struggle for control over representation between gay people and Francoist state agents. Gay narrations of self did not always involve a negation of Catholic dogma, ...

Nachweis des di-2-cyanoisopropylperoxides bei der zersetzung von azoisobuttersäuredinitril in gegenwart von sauerstoff

1970

Das Di-2-cyanoisopropylperoxid entsteht in etwa 5-proz. Ausbeute bei der Zersetzung von Azoisobuttersaredinitril unter Sauerstoff in Isobutyronitril als Losungsmittel. Thermisch zerfallt das Peroxid est oberhalb von 120°C mit mesbarer Geschwindigkeit in einer Reaktion erster Ordnung. Die Aktivierungsenergie, in Cumol als Losungsmittel, wurde zu 37,9 kcal · mol−1 bestimmt. Werte fur die Zerfallskonstante bei 140°C sind in Cumol 0,057 h−1, in tert-Butylbenzol 0,073 h−1, in Chlorbenzol 0,18 h−1 und in o-Dichlorbenzol 0,23 h−1. Di-2-cyanoisopropylperoxide is formed when azobisisobutyronitrile is decomposed under oxygen in isobutyronitrile as a solvent. The yield amounts to ca. 5%. Thermal decom…

Specific recognition of fluoride anion using a metallamacrocycle incorporating a uranyl-salen unit

2008

The design and synthesis of a novel fluoride receptor that uses a salen-complexed Lewis acidic uranyl center as the sole binding site is reported here. This receptor binds fluoride anions in DMSO with a high affinity constant (K > 106 M-1) and exhibits a negligible affinity (K < 10 M-1) towards otherwise effective competitors, such as acetate, phosphate and cyanide anions.

Binding properties of mono-6-amino-beta-cyclodextrin towards p-nitroaniline derivatives: a polarimetric study

Complementarity of reaction force and electron localization function analyses of asynchronicity in bond formation in diels-alder reactions

2014

We have computationally compared three Diels-Alder cycloadditions involving cyclopentadiene and substituted ethylenes; one of the reactions is synchronous, while the others are slightly or highly asynchronous. Synchronicity and weak asynchronicity are characterized by the reaction force constant κ(ξ) having just a single minimum in the transition region along the intrinsic reaction coordinate ξ, while for high asynchronicity κ(ξ) has a negative maximum with minima on both sides. The electron localization function (ELF) shows that the features of κ(ξ) can be directly related to the formation of the new C-C bonds between the diene and the dienophile. There is thus a striking complementarity b…

Multi-language translation and cross-cultural adaptation of the OARSI/OMERACT measure of intermittent and constant osteoarthritis pain (ICOAP).

2009

Summary Aim To conduct a multi-language translation and cross-cultural adaptation of the Intermittent and Constant OsteoArthritis Pain (ICOAP) questionnaire for hip and knee osteoarthritis (OA). Methods The questionnaires were translated and cross-culturally adapted in parallel, using a common protocol, into the following languages: Czech, Dutch, French (France), German, Italian, Norwegian, Spanish (Castillan), North and Central American Spanish, Swedish. The process was conducted following five steps: (1) – independent translation into the target language by two or three persons; (2) – consensus meeting to obtain a single preliminary translated version; (3) – backward translation by an ind…

Response ofBacillus subtilis spores to dehydration and UV irradiation at extremely low temperatures

1996

Spores of Bacillus subtilis have been exposed to the conditions of extreme dehydration (argon/silica gel; simulated space vacuum) for up to 12 weeks at 298 K and 80 K in the dark. The inactivation has been correlated with the production of DNA-double strand-breaks. The temperature-dependence of the rate constants for inactivation or production of DNA-double strand-breaks is surprisingly low. Controls kept in the frozen state at 250 K for the same period of time showed no sign of deterioration. In another series of experiments the spores have been UV irradiated (253.7 nm) at 298 K, 200 K and 80 K after exposure to dehydrating conditions for 3 days. Fluence-effect relationships for inactivati…