Showing papers by "University of Münster published in 1976"

Electrochemical methods for studying diffusion, permeation and solubility of hydrogen in metals

Abstract: Electrochemical methods for the investigation of metal-hydro gen systems are superior to other techniques, e.g., gas-volumetric, because of their simple procedure and their flexibility towards variation of experimental conditions. Moreover, these techniques allow measurements at very low hydrogen equilibrium pressures which occur, for instance, in the V(a)-metal-hydrogen systems in the concentration range of ideal dilute solutions at normal temperatures. The removal of surface layers, which retard the hydrogen passage from the electrolyte into the metal and vice versa, is a necessary condition for electrochemical methods to be applicable. Using ultra-high-vacuum techniques, surface hindrances on base metals like V, Nb, Ta, Ti, and others, can be eliminated. Thus, it is possible to study diffusion, permeation, and solubility of hydrogen (isotopes), in these metals as well as in precious metals such as palladium and its alloys. Various electrochemical hydrogen-diffusion and permeation methods are presented and compared. Their applicability and the limits of application are demonstrated for pre-selected systems. A recently developed electrochemical technique for measuring hydrogen (isotope) solubility in transition metals is described. By means of this method, pressure-concentration equilibrium isotherms of V, Nb, and TaH systems have been obtained recently, at ordinary temperatures, from vanishingly low hydrogen concentrations, corresponding to extremely low equilibrium pressures, up to atomic ratios H/Me of 0.5.

Secondary-ion emission of amino acids

Abstract: Secondary-ion mass spectroscopy (SIMS) is a hydrogen, isotope and compound sensitive analytical technique of extremely high absolute sensitivity. Continuing earlier measurements for carboxylic acids, adsorbed alcohols etc., we have carried out a systematical investigation of secondary-ion emission from metal-supported amino acids, containing various functional groups (e.g., alanine, phenylalanine, cysteine, arginine). In order to avoid damage effects we applied extremely small primary-ion current densities in the 10−9 A·cm−2 range. The main results of our investigations can be summarized as follows: We infer from these results that static SIMS is an excellent tool for trace detection, structural investigation and surface reaction studies of amino acids.

The biological role of octopine in the squid,Loligo vulgaris (Lamarck)

Abstract: The enzymatic activities of glyceraldehyde-3-phosphate dehydrogenase, octopine dehydrogenase and lactate dehydrogenase were determined fromLoligo vulgaris. Octopine dehydrogenase displays the highest activity yet recorded for this enzyme, exceeding glyceraldehyde-3-phosphate dehydrogenase sixfold and lactate dehydrogenase 365-fold (Table 1).

Experimental analysis of the prey catching behavior ofHydromantes italicus Dunn (Amphibia, Plethodontidae)

Abstract: 1. The Italian bolitoglossine salamanderHydromantes italicus shows a periodic cave life. In spring and in the fall it leaves the caves after which it lives under stones, in leaves and crevices. Inside the limestone caves,H. i. can be found both in the zone of dim light near the entrance and in total darkness. 2. Corresponding to these two environments there are two guidance systems of the prey catching behavior: one visual and one olfactory. 3. The visually guided prey catching behavior is determined by the stimulus parameters: velocity, size, contrast, and ambient illumination. Continuously moving objects are effective within a velocity range of 0.05 to 6 cm/s with an optimum at 1.25 cm/s (Fig. 2). Stimuli moving stepwise elicit fixation of the prey and complete approach more frequently than continuously moving stimuli. The prey size which elicits prey catching ranges from 0.5 to 10 mm2 with an optimum size between 2.5–5.0 mm2 (Fig. 3). The prey catching behavior is hardly impaired by a decrease in ambient illumination down to 0.03 cd/m2. Beyond 0.03 cd/m2, the prey catching activity decreases sharply, but there are still responses at an illumination level of 0.003 cd/m2 (Fig. 4). 4.H.i. also responds to stationary non-smelling visual stimuli following stimulation by smell or movement.H.i. is able to detect prey by smell only both in total darkness and in the light (Fig. 5 A). In the light, the prey catching behavior with regard to smelling objects is inhibited by the absence of visual contrast (Fig. 5B).

Untersuchungen zum anaeroben Glykogenabbau beiTubifex tubifex M.

Abstract: 1. The activities of glycolytic enzymes and of related enzymes of anaerobic carbohydrate metabolism were determined inTubifex. The complete line of glycolytic enzymes was detected (Table 1). Only very little lactate dehydrogenase activity could be detected, while high activities of enzymes essential for the production of alanine and succinate are present. 2. Under anaerobic conditions, lactate, alanine, succinate and volatile fatty acids are formed from14C-labeled glucose (Tables 2 and 3). 3. Glycogen degradation was measured under anaerobic conditions (Fig. 1). 4. During anaerobiosis a significant increase of alanine, succinate, propionate and acetate was found. However, the concentration of lactate increased only slightly. After an initial increase within the first 24 h of anaerobiosis, the concentration of alanine remained constant. Succinate, on the other hand, accumulated continuously during 48 h of anaerobiosis, reaching concentrations of 150 μmol/g dry weight (Table 4, Fig. 2). 5. The major end products of fermentation were identified as propionate and acetate. Both are excreted in substantial amounts (Table 5). 6. The amount of anaerobic end products equals the amount of glycogen metabolized (Table 6).

Protophane und Polyaromaten, XXII. Nucleophile Alkylierung und Arylierung des 2,2′‐Bipyridyls

Abstract: 2,2′-Bipyridyl konnte erstmals nucleophil alkyliert werden. Bei der Umsetzung mit Methyl- und n-Butyllithium entstand je nach den Bedingungen sehr selektiv die 6-Alkyl- oder 6,6′-Dialkyl Verbindung (41—64%). Die Anwendung relativ tiefer Temperaturen erlaubte in mittlerer Ausbeute auch die Darstellung von 6-Aryl-Verbindungen (Aryl = Phenyl, 2-Pyridyl). Im Konkurrenzversuch zeigte 2,2′-Bipyridyl gegenuber n-Butyllithium deutlich hohere elektrophile Aktivitat als Pyridin.

Degradation products from aflatoxin B1 byCorynebacterium rubrum, Aspergillus niger, Trichoderma viride andMucor ambiguus

Abstract: Degradation of aflatoxin B1 byCorynebacterium rubrum and byAspergillus niger was analysed by adding14C-labeled aflatoxin B1 to cultures of these microorganisms. Two blue fluorescent compounds, formed byA. niger from aflatoxin B1 with Rf-values 0.42 and 0.48 (Rf of aflatoxin B1=0.54) were accumulated and characterized by UV-, fluorescence and mass spectrometry. Based on their properties both products were identified to be aflatoxin Ro. Under the same conditionsMucor ambiguus andTrichoderma viride also produced aflatoxin Ro.

Arterio-venous anastomoses in rainbow trout gill filaments: a scanning and transmission electron microscopic study.

Abstract: The origin of arterio-venous anastomoses, connecting the efferent filament artery (EFA) with the central venous sinus (CVS) of gill filaments can be well discerned by scanning electron microscopy in the rainbow trout. Corresponding vessels between the afferent filament artery and the CVS could not be detected with the techniques applied. AVA-specific endothelial cells are characterized by their bulky shape and their microvillous surface. The general morphology of AVA's in Salmo gairdneri is very similar to that of AVA's in Tilapia mossambica (Vogel et al., 1974) but they are much longer in the trout. No filament whorls have been encountered in AVA endothelia of Salmo gairdneri.

Transmission microscopy of freeze dried, unstained epiphyseal cartilage of the guinea pig.

Abstract: The question of the initial mineralization in the epiphyseal plate has been investigated to date in specimens prepared by conventional electron microscopical techniques. As conventional techniques can produce artifacts, either a loss of mineral substance or a secondary nucleation, the mineralization process was investigated using freeze dried, vacuum embedded growth cartilage which was neither contrasted nor stained and which had a very short contact with water. The prevailing theory that the first mineralization begins within extracellular matrix vesicles and that the mineralization outside these vesicles is a secondary process was confirmed. Mineralized matrix vesicles were found in the fully mineralized long septa down to the opening zone. In several cases a mineralization could be observed in those transverse septa in which organic substance was present between the cells. The typical radial arrangement of the apatitic needles and platelets in the matrix vesicles could be explained by the formation of a mineralization in an ionotropic gel, the orientation of the matrix macromolecules to be produced by a vectorial influx of calcium ions and phosphate groups coming from different directions. Thin strands of mineral substance with low contrast, which follow the direction of the longitudinal septum, were assumed to be the mineralized collagen fibrils. In several needles dot-like formations were seen and the distance between the middle of neighbouring dots was found to lie mainly in the range 30–56 A, while the lateral separation distance between the middle of closely packed parallel chains and needles was found to lie mainly in the range 30-42 A. Parallel periodic structures which could be visualized in apatitic chains and needles 20–40 A in diameter were assumed to be the 8.2 A-(100)-lattice planes of apatite, being an indication that these formations already possess criteria of the apatite lattice.

11B and 27Al NMR studies of glasses in the system Na2OB2O3Al2O3 (“NABAL”)

Abstract: 11B and 27Al nuclear magnetic resonances (NMR) in glasses of the NABAL system Na2OB2O3Al2O3 have been studied as a function of composition. From the boron data, the fraction of four-coordinated BO4 units has been determined via computer analysis of the NMR spectra; the method is similar to that employed previously for binary and other ternary borate glasses. The 27Al NMR indicates no abrupt change in the average aluminum environment. Certain linear relationships have been found which yield detailed information on the competing processes of BO3, BO4 and AlO4 formation, and the formation of triclusters consisting of three tetrahedra having one oxygen in common. Furthermore, it is concluded that the oxygen available for the formation of various aluminum-containing species is a function of the soda concentration only and that the conversion to AlO4 is favored as compared with BO4.

Capsule shedding in tetrahymena.

Abstract: formed after spraying. Again many branches at 100 ppm and some at 30 ppm were stunted. The effect of chlorflurenol was persistent because growth retardation of stunted branches continued for at least 4 months after spraying. Application of 10 ppm spray to these two cultivars resulted in 2 to 3 times as many new normal shoots as on control plants indicating that chlorflurenol sprays of about this concentration could be used to increase branching in evergreen azaleas. Higher concentrations should be avoided because of the undesirable side effects of leaf curling and growth retardation.

Identification of two urine metabolites of vinyl chloride by GC-MS-investigations

Abstract: Thiodiacetic acid and S-(carboxymethyl)cysteine are found in the urine of rats after a 48 h exposure to 1000 ppm vinyl chloride. The structure of both compounds could be clarified by GC-MS investigations. Chloroethylene oxide, chloroacetaldehyde and chloroacetic acid are assumed to be intermediates in vinyl chloride metabolism. Compounds which can be transformed to one of these alkylating agents in vivo should also lead to renal excretion of thiodiacetic acid and S-(carboxymethyl)cysteine.

Belegung von Kapillarsäulen aus Glas nach Aufbringen von kolloidaler Kieselsäure

Abstract: Zur Belegung von Dunnfilmkapillarsaulen aus Borosilikatglas wird ein praktikables Verfahren beschrieben. Die Benetzbarkeit mit einer Reihe von Phasen wird durch Aufbringen einer sehr dunnen Zwischenschicht von kolloidaler Kieselsaure erhoht. Um auch polarere Verbindungen, wie Fettsauremethylester, Alkohole, Phenole u. Carbonsauren storungsfrei trennen zu konnen, werden einige Desaktivierungsverfahren angegeben.

The end-products of anaerobic carbohydrate metabolism in the larvae ofChironomus thummi thummi

Abstract: 1. The carbohydrate metabolism of the larvae ofChironomus thummi was investigated during periods of experimental anaerobiosis. 2. 600 to 700 μmoles of glycogen/g d.w. were utilized during 48 h of anaerobiosis while about 100 μmoles/g d.w. were used under aerobic conditions. Maximum rates of glycogenolysis occurred during the first 12 h of anaerobiosis. 3. Alanine, lactate, succinate and ethanol accumulated in the larvae. Increases in alanine concentration were very high during short-term anaerobiosis. 4. Large quantities of ethanol were found in the water in which the larvae had been incubated anaerobically: 260 μmoles/g. d.w. after 12 h and up to 1070 μmoles/g d.w. after 48 h. Alanine and succinate were never accumulated in the water although occasionally there were small amounts of lactate. 5. The possibility that microorganisms might be responsible for the formation of ethanol seems to be excluded.

Differential cross sections for elastic electron scattering. II. Charge cloud polarization in N2

Abstract: Relative elastic differential cross sections for electron scattering from N2 molecules have been measured with a crossed beam technique in order to investigate the influence of charge cloud polarization. The angular range studied was 3 to 135 deg and the electron energies were betwee 90 and 1000 eV. Comparison with theoretical calculations based on the independent atom model using partial wave atomic scattering factors shows strong deviations at small scattering angles. This discrepancy is discussed from the point of view of charge cloud polarization. It is found that calculations including an additional polarization potential improve the theoretical description of the experimental small angle data.

Concentration Dependent Uptake of Copper by Barley Roots

Abstract: The time course of the uptake of copper by excised barley roots (Hordeum distichum L.) after 24 h shows different characteristics than after 2 h. A further investigation of the concentration dependent uptake of copper by intact roots and kinetic analysis demonstrates a biphasic pattern for 2 h uptake periods, and possibly monophasic behavior for uptake periods of 20 min and 24 h. Plasmolysis data of cortex cells of barley roots indicate that concentrations above 80 ..mu..M Cu are unphysiological with regard to longer uptake periods.

Immunofluorescence Studies on Pathologic Routine Material: Application to Malignant Lymphomas

Abstract: Summary In an attempt to apply immunmorphologic techniques to pathologic routine material, malignant lymphomas of the Non-Hodgkin- and the Hodgkin-type were studied by indirect immunofluorescence. To minimize nonspecific background staining formalin fixed paraffin sections were treated with protease prior to incubation with the antisera. The usefullness of this procedure in providing additional diagnostic criteria was tested on specimens of malignant lymphomas (chronic lymphocytic leukemias, immunocytic lymphomas, plasmocytic lymphomas, centrocytic lymphomas, centroblastic-centrocyctic lymphomas, centroblastic lymphomas, immunoblastic lymphomas, lymphoblastic lymphomas of Burkitt, convoluted and unclassified type, Hodgkin’s disease). In addition, cases of nonspecific lymphadenitis were studied. The discrimination of single cells particularly of the B-cell line was facilitated using immunofluorescence and different patterns were easily recognized thus aiding the diagnosis based on light microscopic criteria. In addition, preliminary evidence was obtained that lymphoblastic lymphomas categorized as “others” may be further characterized.

Untersuchung des Löslichkeitsverhaltens von Wasserstoff in Vanadin, Niob und Tantal mit einem elektrochemischen Verfahren

Abstract: Durch Anwendung der UHV-Technik Ausheizen von Metallproben und anschliesendes beidseitiges Bedampfen mit einem Pd-Schutzfilm im UHV lassen sich Hemmungen des Wasserstoffdurchtritts auch bei unedlen Metallen wie V, Nb oder Ta weitgehend beseitigen, so das Gleichgewichtsmessungen bei normalen Temperaturen mit einem neu entwickelten elektrochemischen Verfahren moglich sind. Es konnten auf diese Weise p-n-Gleichgewichtsisothermen von sehr kleinen Wasserstoff-Konzentrationen entsprechend extrem niedrigen Gleichgewichtsdrucken bis zu Wasserstoff-Gehalten von etwa MeH0,5 gemessen werden. Fur die Standard-Losungsenthalpie und die Standard-Losungsentropie von Wasserstoff ergaben sich fur die drei Metalle annahernd ubereinstimmende Werte: Unter Berucksichtigung der Elektronenanteile sowie der Schwingungs- und Gitterverzerrungsanteile zur partiellen molaren Entropie des im Metall gelosten Wasserstoffs wird aus dem Verlauf der Konfigurationsentropie mit dem Atomzahlverhaltnis H/Me die Zahl der pro Metallatom besetzbaren Zwischengitterplatze diskutiert. Applying ultra-high-vacuum techniques surface hindrances of base metals like V, Nb and Ta can be eliminated by outgassing the foils at high temperatures and subsequently protecting the clean samples against the formation of new oxide layers with a vapor deposited thin film of Pd on both sides. Samples prepared in that manner are suitable for equilibrium measurements at normal temperatures applying a new developed electrochemical method. p-n-equilibrium isotherms were measured in the concentration range from very small hydrogen concentrations corresponding to extremly small equilibrium pressures up to hydrogen atom to metal atom ratios of 0.5. The standard partial molar enthalpy ΔH0 and entropy ΔS0 of solution (ideal dilute solution) correspond fairly well for the three metals investigated (V, Nb and Ta): Considering the partial molar entropy of hydrogen in the metal as the sum of an electronic, a vibrational, a lattice dilation, and a configurational term the number of available sites per metal atom for hydrogen will be discussed according to the course of the configurational entropy with the hydrogen concentration.

Intermolecular interactions of benzene and carbon tetrachloride with selected free radicals in solution as studied by 13C and 1H dynamic nuclear polarization

Abstract: Intermolecular hyperfine coupling between 13C nuclei and free-radical unpaired electron spins has been examined for six combinations of three free radicals and two solvent molecules. From magnetic ...

Iridoide, V Biogeneseähnliche Synthese von Secologanin‐ und Swerosid‐aglyconmethyläther

Abstract: Umsetzung des “trans”-p-Toluolsulfonates 9b mit Natrium-methylsulfinylmethid in Dimethylsulfoxid fuhrte neben Kondensationsprodukten zum δ,ϵ-ungesattigten Aldehyd 12a. Die baseninduzierte Reaktion des “cis”-p-Toluolsulfonates 10b ergab dagegen durch intramolekulare Susbtitution ausschlieslich das Oxetan 13. In analoger Weise reagierte das Hydroxyloganin-Derivate 16c zum Oxetan 18, wahrend das 6-Epihydroxyloganin-Derivat 15c mit 67% Ausbeute zum Secologanin-aglyconmethylather (1b) gespalten werden konnte. In Abhangigkeit von den Reaktionsbedingungen wurde hierbei als zweites Produkt das Secologaninsaure-Derivat 20a gebildet, das sich mit Natriumborhydrid zur Hydroxycarbonsaure 24 reduzieren und durch anschliesende Destillation in den Swerosid-aglyconmethylather 2b uberfuhren lies. Die Reduktion von 1b fuhre direkt zu 2b. Iridoide, V Biogenetic Type Synthesis of Secologanin- and Sweroside Aglycone O-Methyl Ether Reaction of the “trans”-p-toluenesulfonate 9b with sodium methylsulfinylmethide in dimethyl sulfoxide gave the δ,ϵ-unsaturated aldehyde 12a besides polymeric products. On the other hand treatement of the “cis”-p--toluenesulfonate 10b with base yielded by intramolecular nucleophilic substitution only an oxetane 13. According to this the hydroxyloganin derivative 16c led to the oxetane 18, whereas the 6-epihydroxyloganin derivative 15c could be cleaved to secologanin-aglycone O-methyl ether 1b. Depending on the reaction-conditions the secologanic acid compound 20a was formed as a byproduct. 20a could be reduced to the hydroxy acid 24, which was converted to sweroside aglycone O-methyl ether 2b by distillation. Reduction of 1b led directly to 2b.