摘要:

AbstractThe photochromic properties of 1′‐octadecyl‐3′,3′‐dimethyl‐6‐nitrospiro[2H‐1‐benzopyran‐2,2′‐indoline] have been studied in monolayers at the air‐water interface by measuring the surface pressure‐area isotherms and the surface potential of several mixtures of this compound with tripalmitine. By using the Langmuir‐Blodgett technique we have transferred mixed monolayers of tripalmitine and spiropyran in a molar mixing ratio of 6:1 onto glass slides and have studied their photochromic pro

ISSN:0005-9021    

DOI:10.1002/bbpc.19790831203

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1979

数据来源: WILEY

摘要:

AbstractIn relaxation experiments in aqueous micellar solutions one observes two processes. In order to compare the kinetic data obtained by different methods, these processes were investigated usingp‐jump and stopped‐flow as perturbation methods, and conductivity and extinction as detection methods. The agreement is sufficient. — The results for the amplitudes measured in stopped‐flow experiments indicate, that with ionic surfactants the number density of monomers does not remain constant above the cmc, but decreases again with increasing surfactant concentration. The consideration of this fact leads to a qualitative agreement between theory and exp

ISSN:0005-9021    

DOI:10.1002/bbpc.19790831204

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1979

数据来源: WILEY

摘要:

AbstractHauptbestandteile des Wäscheschmutzes bilden ölige und fettige Anschmutzungen, Pigmente sowie lösliche und unlösliche Salze. Farbstoffe als Schmutz nehmen eine Sonderstellung speziell in industriellen Waschprozessen ein. Am Beispiel eines Substantivfarbstoffs wurde die Beeinflussung von Farbstoffgleichgewichten in Waschprozessen durch das klassische lösliche Hilfsmittel Polyvinylpyrrolidon (PVP) und die wasserunlösliche Wirksubstanz Na — Al‐Silikat (SASIL) untersucht. Während PVP im wäßrigen Medium den Farbstoff durch Komplexbildung stabilisiert, verhindert SASIL durch gezielte Abgabe von löslichen Bestandteilen, die mit Farbstoffen und Fasern in Wechselwirkung treten können, das Wiederaufziehen der Farbstoffe auf textile Oberflächen. Kolloidchemische Untersuchungen in Verbindung mit Modellwaschversuchen zeigen, daß beide Substanzen, trotz unterschiedlicher Wirkmechanismen, einen vergleichbaren Einfluß auf die Farbstoffgleichgewichte im wäßr

ISSN:0005-9021    

DOI:10.1002/bbpc.19790831205

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1979

数据来源: WILEY

摘要:

AbstractThe kinetics of one‐step reactions in solution was studied non‐isothermally (linear temperature increase in the external system) by Differential Thermal Analysis (DTA) in an apparatus using a stirring technique. — Based on the assumption of a proportionality between heat flux and reaction rate, experimental DTA curves were evaluated by three methods, a) calculation of rate constants according to the formula proposed by Borchardt and Daniels [9], b) calculation of rate constants from non‐isothermal rate curves deduced from the heat balance equation, c) deriving activation data by optimum fitting of the theoretical model curves generated by numerical integration of the rate law, to the experimental curve. — In all cases studied, results obtained by the three methods are in good agreement. They are also confirmed by values reported in the literature, which are obtained by isothermal methods. However, it is not possible to extract rate constants from the decaying portion of the DTA curves, since the weight of the kinetic information is decreased with reaction progress, whereas the influence of heat conductivity is increased. The nature of the dependence of the usable curve time range on kinetics (reaction order and specific time), cell constant, heating rate, and initial concentration which was tested by re‐evaluation of the theoretically generated curves confirms our model and may serve as independent evidence for the applicability of all three methods even assuming extreme values for relevant

ISSN:0005-9021    

DOI:10.1002/bbpc.19790831206

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1979

数据来源: WILEY

摘要:

AbstractA differential spectrometrical arrangement was used to observe the aggregation of the compounds thymidine‐5′‐β‐(9‐acridylamino)‐ethyl‐phosphate (EAA)pT and 9‐β‐hydroxyethylaminoacridine (HEAA) (Fig. 1) in aqueous solution. The dimerization constant.Kdi, and the change in the extinction coefficient, Δεdi, of both substances were determined over the pH‐range from 7 to 12. A significant pH‐dependence ofKdiwas not observed. The dimerization models for HEAA, two protonation states, and for (EAA)pT, four protonation states, at various pH‐values are discussed. This arrangement has proved to be a sensitive method fo

ISSN:0005-9021    

DOI:10.1002/bbpc.19790831207

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1979

数据来源: WILEY

摘要:

AbstractRelaxation amplitudes of temperature‐jump experiments with non‐resolvable relaxation times were utilized to study equilibrium properties of the compounds thymidine‐5′‐β‐(9‐acridylamino)‐ethyl‐phosphate, (EAA)pT, and 9‐β‐hydroxyethylaminoacridine (HEAA) (Fig. 1) in aqueous solution. The procedure for determining the thermodynamic data of two reactions, a deprotonation and a dimerization, in each compound system by using relaxation amplitudes at various pH‐values have been presented. The thermodynamic data, such as ΔG, ΔH, and ΔSof the two reactions in each system could be separately determined. They are of the same order of magnitude for both compounds at the visible region of the absorption spectra. The conclusion was made that the thymine ring and the acridine dye chromophore do not interfere each other in (EAA)pT molecule for the deprotonatio

ISSN:0005-9021    

DOI:10.1002/bbpc.19790831208

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1979

数据来源: WILEY

摘要:

AbstractAn ultrasonic absorption technique was used to study the dynamic properties of the compound thymidine‐5′‐β‐(9‐acridylamino)‐ethylphosphate, (EAA)pT (Fig. 1), in aqueous solution. The pH and concentration dependence of the relaxation time, τ, and amplitude (α · λ) were investigated. The maximal amplitude of the ultrasonic absorption (α · λ)maxis near the pKof this compound. A pH‐dependence of the relaxation frequencies,fR, cannot be found. Within the narrow concentration range of (EAA)pT, increasing concentrations at constant pH values leads to decreasing relaxation frequencies. All these facts can be explained on the basis of an intramolecular proton exchange between the two single protonated states of (EAA)pT at pH − pK.The accuracy of such an elucidation, and the necessary physical assumptions for this equilibri

ISSN:0005-9021    

DOI:10.1002/bbpc.19790831209

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1979

数据来源: WILEY

摘要:

AbstractThe proton and nitrogen hyperfine splittings of the short‐lived N‐hydropyridinyl radical have been measured over the temperature range ‐80 to 42°C in Propanol(‐2)/Acetone. The ESR‐data of the N‐deuteropyridinyl and the N‐hydropentadeuteropyridinyl radical at 22°C have been determined. The temperature coefficient of the NH proton splitting and the shift in the splitting caused by N‐deuterium substitution are unusually large. The effects of temperature and deuterium substitution have been analyzed using the model of localized out‐of‐plane vibrations of the protons. The estimated frequencies, in units of cm−1, are 290, 490, and 870 for the protons in position 1, 3(5), and 4, respectively. The result is discussed in connection with other ESR and MO studies on N‐hydropyridinyl and N, N′‐dihydrodiazinyl radicals. The previously observed non‐transferability of the spin polarization parameterQHNHis explained by the exceptionally low vibration frequency of the NH proton. A value ofQHNH= −3.1 ± 0.4 mT is derived for the fixed planar structure of the radical. The vibrational analysis also confirms the negative sign of the π‐spin density on

ISSN:0005-9021    

DOI:10.1002/bbpc.19790831210

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1979

数据来源: WILEY

摘要:

AbstractThe molecular mobility of liquid ammonia is derived from the determination of the longitudinal relaxation times of the protons and deuterons. The experiments were performed in the temperature interval between the melting pressure curve and 467 K for NH3and to 351 K for ND3at pressures up to 250 MPa. At temperatures below ∼ 350 K the molecular mobility can be described by the isotropic small‐step diffusion model. The activation energies at constant pressure are derived for the rotatoric diffusion to 7.0 ± 0.5 kJ · mol−1and for the translatoric diffusion to 6 ± 1 kJ · mol−1from the temperature dependence of the relaxation rates. In addition the activation energy at constant volume for the rotatoric diffusion has been determined to 5.7 ± 0.5 kJ · mol−1. The isotherms for all relaxation rates are linear in a log(1/T1) versus 1/Tplot, yielding ΔV≠intra= 2.5 ± 0.6 cm3· mol−1and ΔV

ISSN:0005-9021    

DOI:10.1002/bbpc.19790831211

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1979

数据来源: WILEY

摘要:

AbstractBy means of high‐temperature mass‐spectrometry the gaseous IIB/VIA‐molecules ZnS(g), ZnTe(g), CdTe(g), and HgSe(g) were identified by their isotopic distributions in equilibrium with the corresponding solid chalcogenides. HgTe(g) remains the only MeX(g)‐molecule of the IIB/VIA‐type as yet undetected — suggesting that the remaining eleven IIB/VIA‐molecules may originate from a gas‐phase reaction between Me(g)‐ and Xi(g)‐species which cannot occur in the HgTe‐system due to the absence of gaseous Teiin the eq

ISSN:0005-9021    

DOI:10.1002/bbpc.19790831212

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1979

数据来源: WILEY