Bestimmung der Aktivität von Bleicherden,insbesondere im Hinblick auf ihre Verwendung zur Qualitätsbeurteilung vegetabilischer Öle I

Determination of the Activity of a Bleaching Earth with Respect to its Application in the Quality Assessment of Oils I One of the surest tools for the determination of freshness of raw oils is the determination of extinction in diene and triene region. The oxydative changes, which are rarely detected by the usual analytical characteristics, can be easily recognized in a bleach-test by treating the oil with a definite amount of bleaching earth followed by measurement of increase or decrease in extinction. The general application of this procedure was not feasible till now because the activity of the bleaching earth used for this purpose was unknown or only roughly known. For the determination of the activity of bleaching earths with sufficient accuracy a simple method was developed, which consists of treatment of the bleaching earth with castor oil. The reproducibility of the bleach-test could thus be appreciably improved.     

Catalytic oxidation of 1,2-dichlorobenzene over ABO3-type perovskites

Several ABO₃-type perovskite oxides (A = La, Y, Nd or Gd; B = Fe, Mn, Cr or Co) have been investigated as catalysts for the oxidation of 1,2-dichlorobenzene (o-DCB), a model compound for the highly toxic polychlorinated dibenzodioxins. Initial transient and steady state activity measurements were conducted with all catalysts in the absence and presence of water. Perovskites containing Cr in the B-site were more active than perovskites containing other transition metals, with YCrO₃ being the most active catalyst among the different systems studied. Furthermore, YCrO₃ did not show any loss of its initial activity after several hours on stream. Other perovskites lost 10–20% of their initial activity within the first 5–10 h on stream. This loss was associated with a corresponding loss in BET surface area. With the exception of LaCoO₃, all perovskites retained their crystalline structure upon exposure to o-DCB under reaction conditions. LaCoO₃ was converted to LaOCl and Co₃O₄. The presence of water appeared to enhance the catalytic activity of some perovskites. This effect can be attributed to a faster removal of Cl⁻ ions from the catalyst surface via their reaction with water.     

Usages of the “cultural landscape” concept in Norwegian and Nordic landscape administration

This paper summarizes the results of an analysis of differing usages of the concept of “cultural landscape” and related concepts in Norwegian and Nordic government policy and applied research documents. The analysis indicates how inconsistent or unclear use of concepts can hinder interdisciplinary and intersectorial communication. The role of rhetoric, the changing usage of concepts over time and different value loadings for similar concepts are exemplified. Confusion arises partly because previously separate academic discourses, based on separate but overlapping sets of values, have come together in a common discourse promoted by the application of research to government policy. The principal participants in this discourse are agricultural interests, nature conservation interests, cultural heritage interests and local planning interests.     

Kritische Anmerkungen zur Bestimmung des Restbenzins in Extraktionsschroten

Critical Remarks about Residual Benzine Determination in Extracted Seeds To lower the risk of explosion during upheavel or loading of extracted seeds the precise knowledge of the residual benzine content in the seed is of high importance. To be able to judge the various new analytical methods, the relation between benzine content of the seed and of the surrounding air was studied in extended test series. It was found that both dimensions obey predominantly the law of Freundlich and that the benzine retention is scarcely influenced by kind an loose volume of the extracted seed, but strongly by its fat content. Basing on the results the recent DGF standard method B-II 8a (83) for residual benzine determination in extracted seed (M. Arens and E. Kroll, Fette. Seifen. Anstrichmittel 85 , 307 [1983]) in which the total benzine content is deduced from the benzine concentration in the gas phase determined by gaschromatography, is estimated as very reliable. But the former DGF-method, B-II 8 (68), too, applied for the same purpose, should be kept after some improvements have been carried out, because it demands only a small need of devices.     

Eine empirische Methode zur Bestimmung der Emulgierfähigkeit von Pflanzenlecithinen in O/W-Systemen

An Empiric Method to Determine the Emulsifiability of Vegetable Lecithins in O/W-Systems The following method has been developed to evaluate the emulsifying effect of native, fractionated and modified vegetable lecithins. The lecithin which is to examine is solved in the ratio 1:9 in a fat mixture with the melting point of 32°C and the solution is given on the surface of 50 ml of water with 50°C, in a graduated cylinder. After 30 min. time of rest the cylinder is turned by hand or by means of a mechanic swinging device 20 times in 20 seconds for 180° about its transverse axis. Afterwards it is placed in a thermostat, with a temperature of 50°C. The time necessary to separate 25 ml water is determined. The thus defined half-life is characteristic for the emulsifying effect of the lecithin. The variation coefficient of the results is about 10% for mechanically emulsifying. The practicability of this method is explicated in many examples.     

Some aspects of fracture mechanics research during the last 25 years

A review is given of the various concepts of fracture mechanics, furthermore of their application to assess the toughness of steels and to guarantee the safety of structures containing cracks. The three most important parameters are the stress-intensity factor K_I for linear elastic fracture mechanics (LEFM), the crack tip opening displacement CTOD and the J-integral for elastic-plastic fracture mechanics (EPFM). The ASTM designation E 1820-96 provides a common method for determining all applicable toughness parameters from a single test, including R-curves. Many investigations dealt with the numerous influences on these parameters, e.g. specimen geometry arid temperature and strain rate. Various failure concepts have been developed. The method of LEFM based on plane strain fracture toughness K_Ic is well established for high strength steels or low temperatures. For modern steels with high toughness the more complicated concepts of EPFM have to be applied. Because of the availability of commercial software for FE-calculations the application of the J-integral has become widespread in recent years. A number of approximative methods has been elaborated, e.g. CTOD-design-curve, BSI PD6493:1991, CEGB-R6-method, ETM, Eurocode 3 Annex C. Although the theory of fracture mechanics regards the material as an isotropic continuum the question is of great importance, how its materials parameters depend on the microstructure of the steels. Systematic investigations with the aid of the hot deformation simulator Wumsi showed the favourable material properties of fracture mechanics resulting from thermomechanical treatment. Many models were published for the quantitative correlation between microstructure and toughness parameters, mainly K_Ic. At the moment the modified Gurson model is in widespread use, which allows the prediction of J-R-curves.     

Rhodium‐Catalyzed Bis‐Hydroaminomethylation of Linear Aliphatic Alkenes with Piperazine

An efficient protocol was developed to prepare a series of dialkylpiperazines via Rh‐catalyzed bis‐hydroaminomethylation of linear aliphatic alkenes with piperazine. The well‐known Rh/Biphephos catalytic system was applied, yielding the desired dialkylpiperazines within six tandem catalytic steps, already at low catalyst loadings of 0.1 mol%. For the model alkene 1‐octene, good yields and linearities of 80% and 77:23, respectively, were achieved under optimized conditions. Influences on the catalytic system regarding n/iso ratio, possible side reactions and the reaction path are discussed on the basis of yield vs. time plots and parameter optimization. With the developed general protocol, other linear, functionalized and branched substrates were effectively transformed to the corresponding linear N,N‐disubstituted piperazines.

     

Analysis and sorption of psychoactive drugs onto sediment

An analytical method was developed to analyze eight psychoactive pharmaceuticals--including the antiepileptic carbamazepine, the opiates morphine, codeine, dihydrocodeine, the opiode tramadol, and the tranquilizers diazepam, oxazepam, temazepam--and the antibiotic sulfamethoxazole as well as three metabolites (10,11-dihydrocarbamazepine (DHC), 10,11-dihydroxy-10, 11-dihydrocarbamazepine, and N4-acetylsulfamethoxazole) in river sediments. Relative recoveries of all analytes exceeded 97% using either deuterated or 13C15N-labeled surrogate standards. Sorption isotherms of all analytes were constructed at pH 6.5-6.6 on two natural river sediments (Burgen and Dausenau) that differed in organic carbon contents and particle size distributions. Affinities of all analytes were up to an order of magnitude higher for the Dausenau sediment in comparison to the Burgen sediment. Isotherms were well described by the Freundlich model. Sorption of all analytes was linear on the Burgen sediment except for structurally similar carbamazepine (n = 0.90) and DHC (n = 0.88). Conversely, most analytes showed pronounced nonlinear sorption to the Dausenau sediment (n = 0.77-0.92) except for positively charged codeine, dihydrocodeine, and tramadol. Linear sorption of the latter was taken to arise from concentration-independent electrostatic interactions of the organocations with negatively charged surfaces on clay minerals or in the sediment organic matter. Desorption gave rise to hysteresis in 13 out of 16 investigated analyte-sorbent systems. Hysteresis was likely due to slow desorption kinetics beyond 24 h used in the experiment.