Showing papers by "Martin Luther University of Halle-Wittenberg published in 1980"
113 citations
TL;DR: In this article, the synthesis of disubstituted 1,3,4 and 1,2,4-thiadiazoles and their melting and clearing points are investigated and the influence of the heterocyclic ring system on the formation of crystalline liquid phases is discussed.
Abstract: Liquid Crystalline 1,3,4-Thiadiazoles. I. Biphenyl- and Terphenyl Analogous 1,3,4-Thiadiazoles
The synthesis of disubstituted 1,3,4- and 1,2,4-thiadiazoles and 1,3,4-oxadiazoles is described and their melting and clearing points are investigated. The influence of the heterocyclic ring system on the formation of crystalline liquid phases is discussed.
95 citations
TL;DR: In this paper, the phase transitions were confirmed by microscopic and calorimetric (Perkin Elmer DSC 2) measurements in some homologous series and the phase transition was shown to be stable.
Abstract: This preliminary publication will give information on the phase transitions which we confirmed by microscopic and calorimetric (Perkin Elmer DSC 2) measurements in some homologous series.
89 citations
TL;DR: The authors' results show a stimulation of the second step in PGI2 biosynthesis (from endoperoxides) by dipyridamole, which should be considered in relation to the therapeutic usage of the drug in myocardial infarction.
Abstract: 1 Dipyridamole (0.01 to 0.75 mM) increased prostacyclin (PGI2) biosynthesis from tritiated arachidonic acid in rat stomach fundus homogenates by 21 to 350%. The transformation of prostaglandin H2 (PGH2) to PGI2 by a microsomal fraction of pig aorta was stimulated by dipyridamole at 0.1 M by 63%. 2 In the isolated perfused heart of the rabbit dipyridamole at 1 and 5 micrograms/ml increased PGI2 release by 70% and 146% respectively. 3 Our results show a stimulation of the second step in PGI2 biosynthesis (from endoperoxides) by dipyridamole. This effect should be considered in relation to the therapeutic usage of the drug in myocardial infarction.
86 citations
TL;DR: A very low concentration of LDL cholesterol and a high concentration of HDL cholesterol stimulated prostaglandin I2 synthesis, whereas a high LDL cholesterol concentration inhibited prostaglanders I2 biosynthesis by 64%.
75 citations
61 citations
TL;DR: SBN 75 and PLZT 8/65/35, two ferro-electrics with different structure and symmetry which exhibit diffused phase transition, show similar aging effects: a lessening of the dielectric losses and of the Dielectric dispersion by lowering the low-frequency dielectoric constant (DC), a doubling of the hysteresis loop within the slim loop region, a lowering of the transition temperature Tt and special features in the field dependence of the DC as mentioned in this paper.
Abstract: SBN 75 and PLZT 8/65/35, two ferroelectrics with different structure and symmetry which exhibit diffused phase transition, show similar aging effects: a lessening of the dielectric losses and of the dielectric dispersion by lowering the low-frequency dielectric constant (DC), a doubling of the hysteresis loop within the slim loop region, a lowering of the transition temperature Tt and special features in the field dependence of the DC The results are discussed in terms of the two-level relaxation model proposed by Reinecke and Ngai
SBN 75 und PLZT 8/65/35, zwei Ferroelektrika mit unterschiedlicher Struktur und Symmetrie, die jedoch beide eine diffuse Phasenumwandlung aufweisen, zeigen ahnliche Alterungseffekte: eine Verringerung der dielektrischen Dispersion — durch Erniedrigung der niederfrequenten Dielektrizitatskonstante — sowie der dielektrischen Verluste, eine Verdoppelung der Hysteresekurven im Gebiet der schmalen Schleifen, eine Erniedrigung der Ubergangstemperatur Tt sowie spezielle Erscheinungen in der Feldstarkeabhangigkeit der Dielektrizitatskonstante Die Ergebnisse werden an Hand eines Relaxationsmodells auf der Grundlage von Zwei-Niveau-Systemen diskutiert, wie es Reinecke und Ngai vorgeschlagen haben
54 citations
TL;DR: The action of cathepsin L on the oxidized insulin B-chain has been studied in order to elucidate the specificity of cleavage by this proteinase and suggest the amino acid sequence of possible specific synthetic substrates and inhibitors.
53 citations
TL;DR: In this paper, the structures of compounds I and II are discussed on the basis of their NMR spectra and the reaction with methanol leads to PH-functional derivatives.
44 citations
TL;DR: Some homologous 4n-Alkyloxy-benzoyloxy]-benzylidene-4′-cyanoanilines are presented in this paper.
Abstract: Some homologous 4[4-n-Alkyloxy-benzoyloxy]-benzylidene-4′-cyanoanilines are presented. Three of them exhibit a reentrant nematic phase. For the decyloxy compound the variant of polymorphism Nre SC SA N is. was found.
44 citations
TL;DR: In this paper, Ramaman and Brillouin scattering studies have been made in ferroelectric and paraelectric phases of TSCC and an attempt is made to interpret the obtained experimental results by a model of improper Ferroelectric phase transition.
Abstract: Raman and Brillouin scattering studies have been made in ferroelectric and paraelectric phases of TSCC. An attempt is made to interpret the obtained experimental results by a model of improper ferroelectric phase transition.
TL;DR: In this article, the authors investigate the kinetics of phase transitions, in which smectic D is participating, showing a strong dependence upon the experimental conditions, such as supercooling, as well as overheating effects.
Abstract: The substances of the homologous series
with n = 6, 12, 14, 15, 16, 18 were investigated by calorimetry and microscopy. In the lower members exist nematic, smectic A and smectic C phases, in the homologs with n = 16 and 18 appear phases of the type smectic D with cubic structure. The kinetics of these phase transitions, in which smectic D is participating shows a strong dependence upon the experimental conditions. Supercooling, as well as, overheating effects were found. In the supercooled state we could detect for the first time smectic phases, which are metastable with respect to another liquid crystalline phase (SD).
Die Substanzen der homologen Reihe
mit n = 6, 12, 14, 15, 16, 18 wurden kalorimetrisch und mikroskopisch untersucht. An den niederen Gliedern treten nematische und smektische A- und C-Phasen auf, an den Homologen mit n = 16 und 18 existieren Phasen des Typs smektisch D mit kubischer Struktur. Die Kinetik der Phasenumwandlungen, an welchen smektisch D beteiligt ist, zeigt eine starke Abhangigkeit von den experimentellen Bedingungen und last sowohl Unterkuhlungs- als auch Uberhitzungserscheinungen erkennen. Im unterkuhlten Zustand konnten erstmals smektische Phasen nachgewiesen werden, die gegenuber einer anderen kristallin-flussigen Phase (SD) metastabil sind.
01 Jan 1980
TL;DR: In spite of the great ecological importance of the Red Fox, very little research work has been undertaken to clarify the population ecology of the predator in Northern Central Europe as discussed by the authors, and only a very small amount of data has been collected.
Abstract: The Red Fox is distributed throughout the GDR. From 1968 to 1977 an average of 56,773 specimens were shot annually. In spite of the great ecological importance of the Red Fox only a very little research work has been undertaken to clarify the population ecology of the predator in Northern Central Europe.
TL;DR: Aromatic primary phosphines react with carboxylic acid amide acetals to give aryldialkylaminoalkylidenphosphines as discussed by the authors, and extensive 1H, 13C and 31p nmr studies prove the compounds to involve phosphorus in the trivalent dicoordinate state.
TL;DR: In this paper, the temperature dependence of the dielectric constant, polarization, and elastic compliance as well as the field dependence of polarization and strain at different temperatures were measured at lead magnesium niobate single crystals for three different directions.
Abstract: The temperature dependence of the dielectric constant, polarization, and elastic compliance as well as the field dependence of the polarization and strain at different temperatures was measured at lead magnesium niobate single crystals for three different directions. From the results some conclusions with respect to the symmetry of the field-induced ferroelectric phases can be drawn. Below −70°C and after complete poling, the spontaneous polarization is probably directed along [111].
An Bleimagnesiumniobat-Einkristallen wurden die Temperaturabhangigkeit der Dielektrizitatskonstanten, der Polarisation und der elastischen Nachgiebigkeit sowie die Feldstarkeabhangigkeit der Polarisation und der Dehnung bei verschiedenen Temperaturen gemessen, und zwar bei drei verschiedenen Feldrichtungen. Die Ergebnisse ermoglichen einige Aussagen bezuglich der Symmetrie der feldinduzierten ferroelektrischen Phasen. Unterhalb −70°C und nach vollstandiger Polung ist die Richtung der spontanen Polarisation wahrscheinlich parallel [111].
TL;DR: In this article, the reaction of N-acylimino-dithiocarbonic-acid-S,S-diesters with nucleophilic com-pounds presents new possibilities to synthesize heterocycles.
Abstract: Reactions with N-Acylimino-dithiocarbonic-acid-diesters.
Reactions of N-acylimino-dithiocarbonic-acid-S,S-diesters 1 with nucleophilic com-pounds present new possibilities to synthesize heterocycles. With amines 1a reacts by mono- and disubstitution, respectively, of methylthio-groups to isothioureas 2 and guanidines 3, with 1,2-bi-nucleophilic arenes to benzoheterocycles 4, with aliphatic diamines to imidazolidines 5, pyrimidines 6, diazepines 7 and the hexamethylene-diamine-derivatives 8. 1a reacts also with hydrazines to 1,2,4-triazoles 9 and with hydrazides to the thiosemicarbazones 10 or 1,3,4-oxadiazoles 11. Heterocyclisations of 1 with guanidines, thiourea, salts of thiourea and amidines give the 1,3,5-triazines 12, 14, 15 and 16. N-benzoyl-dithiocarbonic-acid-methylester -amid reacts with CH-acidic compounds to thiazoles 17. The structures of the final products are determined by i.r.-, 1H-n.m.r.-, u.v.- and mass-spectras.
TL;DR: In this paper, a modified Mannich reaction was used to transform α-Aminoacids, their esters and sodium salts into N -phosphinomethyl or N,N -bis(phosphine) derivatives, and the highest optical yield achieved was 29%.
TL;DR: In this paper, X-ray studies in oriented and not oriented samples of n-pentyl 4-[4-n-dodecyloxybenzylidene-amino] -cinnamate are reported.
Abstract: Results of X-ray studies in oriented and not oriented samples of n-pentyl 4-[4-n-dodecyloxybenzylidene-amino] -cinnamate in the smectic modifications I, C and A respectively are reported. Special emphasis is led to the SI phase, the structure of which is determined to be monoclinic with parameters a=5.04A; b=8.40 A c=37.8 A; s= 106°. An attempt was made to present a model of the packing of the molecules regarding shifts of the molecules, too.
TL;DR: In a comparison between the two population groups the frequency of traumatized permanent maxillary incisors with greater tooth loss (types 3 + 4) were significantly higher in Iraqi than in Sudanese children with protrusion and inadequate lip coverage.
Abstract: A comparative epidemiologic study on traumatized permanent anterior teeth was conducted on 6090 Iraqi and 3507 Sudanese primary schoolchildren. A significant relationship was found between the severity of trauma to protrusion of maxillary incisors and amount of lip coverage in Iraqis and a similar tendency was observed for the Sudanese. In a comparison between the two population groups the frequency of traumatized permanent maxillary incisors with greater tooth loss (types 3 + 4) were significantly higher in Iraqi than in Sudanese children with protrusion and inadequate lip coverage.
TL;DR: In this paper, the interfacial behavior of Dipalmitoyllecithin (DPPC) was investigated on mercury electrode/alcohol solutions and its adsorption on both positively and negatively charged electrodes was described.
TL;DR: In this article, the nmr data of the compounds are discussed and the nmR data of all the compounds is discussed in detail, including the reaction with carboxylic ester amide acetals or benzaldehyde to give 1.3-benzothiaphospholes.
TL;DR: Both the inactivation constants as well as the relative concentrations of the enzyme fractions were found to change in dependence on temperature.
Abstract: The thermal inactivation kinetics of chymotrypsin, trypsin, and—-amylase bound to silica, polyacrylamide, and polystyrene were studied at different temperatures. The inactivation curves were analyzed by a kinetic model, assuming a first-order reaction of differently stable enzyme fractions on the matrix. In all cases the assumption of two enzyme fractions with distinctly different inactivation constants was sufficient for describing the inactivation progress (standard deviations between experimental and calculated inactivation curves, 1-4%). Both the inactivation constants as well as the relative concentrations of the enzyme fractions were found to change in dependence on temperature.
TL;DR: The dielectric properties of four 4n-alkyloxyphenyl 4-nalkyloxybenzoates with nematic, smectic C and partly additional SA phases were investigated in this paper.
Abstract: The dielectric properties of four 4-n-alkyloxyphenyl 4-n-alkyloxybenzoates with nematic, smectic C and partly additional SA phases were investigated. In 2 substances for ϵ′ reproducible values also in the smectic phases resulted allowing to conclude on a good orientation in the samples. In all 4 substances the dielectric relaxation in the MHz region was measured and the respective activation energies were determined. The molecular mobility in the SC phases is higher than in the SA phases, however comparable with that of the nematic phases. In all 3 phase types a single relaxation mechanism exists, which is explained as rotation of the molecules around a short axis.
Die dielektrischen Eigenschaften von 4 4-n-Alkyloxybenzoesaure-4-n-alkyloxyphenyl-estern, welche nematische, smektische C- und teilweise zusatzliche A-Phasen besitzen, wurden untersucht. In 2 Substanzen wurden fur ϵ′ auch in den smektischen Phasen reproduzierbare Ergebnisse erhalten, was auf eine gute Orientierung in den Proben schliesen last. In allen 4 Substanzen wurden die dielektrische Relaxation im MHz-Gebiet gemessen und die zugehorige Aktivierungsenergien in den verschiedenen Phasen bestimmt. Die molekulare Beweglichkeit in den SC-Phasen ist hoher als in den SA-Phasen, jedoch mit derjenigen in den nematischen Phasen vergleichbar. In allen 3 Phasentypen liegt ein einfacher Relaxationsmechanismus vor, der als Rotation der Molekule um eine kurze Achse gedeutet wird.
TL;DR: In this paper, the reactions of o -arsinophenoles with carboxylic acid derivatives were studied and with imidoyl chlorides the aromatic 1,3-benzoxarsoles were obtained.
01 Jan 1980-Zentralblatt für Bakteriologie, Parasitenkunde, Infektionskrankheiten und Hygiene. Zweite Naturwissenschaftliche Abteilung: Mikrobiologie der Landwirtschaft, der Technologie und des Umweltschutzes
TL;DR: Effective N2-fixation requires nodules being a powerful sink for assimilates on the basis of a highly efficient photosynthetic sytem of the host plant and their consumption of photosynthates.
TL;DR: The association behavior of 1-Alkylstannatranes is characterized by molecular mass estimation and 1H-, 13C-, and 119Sn-NMR measurements as mentioned in this paper.
Abstract: Es wird uber einige neue Stannatrane und Thiostannatrane berichtet und gezeigt, das die 1-Alkylstannatrane in unpolaren Losungsmitteln zu relativ stabilen trimeren Einheiten assoziieren. In wasriger Losung zeigt 1-Methylstannatran keine Selbstassoziation. 1-t-Butylstannatran, 1-o-Tolylstannatran und 1-Alkylthiostannatrane sind in allen Losungsmitteln monomer. Das Assoziationsverhalten wird durch Molekulargewichtsbestimmung und 1H-, 13C- und 119Sn-NMR-Messungen charakterisiert.
Association Behaviour of Strannatranes
1-Alkylstannatranes (R = Me, Et, Bu, Phenyl) associate in unpolar solvents to relatively stable trimeric units. In aqueous solution 1-methylstannatran displays no autoassociation. 1-t-Butylstannatran, 1-o-tolylstannatran, and 1-alkylthiostannatranes are monomeric in all kinds of solvents. The association behaviour is characterized by molecular mass estimation and 1H-, 13C-, and 119Sn-NMR measurements.
TL;DR: The structure of Triphenylphosphonio-cyanamid Ph3PNCN has been determined by Patterson and Fourier techniques and refined by least squares methods to R = 0.047 as discussed by the authors.
Abstract: Triphenylphosphonio-cyanamid Ph3PNCN kristallisiert monoklin in der Raumgruppe P21/c mit a = 957,5 pm, b = 1670,4 pm, c = 1126,7 pm, β = 121,28° und Z = 4. Dle Struktur wurde mit Hilfe von Patterson- und Fouriersynthesen bestimmt und nach der Methode der kleinsten Fehlerquadrate bis zu einem R-Wert von 0,047 verfeinert.
Die wichtigsten Bindungslangen und -winkel sind P-N = 159,4 pm, PC = 179,9 pm (Mittelwert), NC = 130,1 pm bzw. 115,1 pm, PNC = 123,0° und NCN = 174,8°. Die Molekulstruktur von Ph3PNCN wird mit der anderer Iminophosphorane verglichen und die Stellung der Verbindung in der Reihe der Triphenylphosphin-pseudochalkogenide diskutiert.
Structure Investigations on Pseudochalcogene Phosphorus Compounds. II. Crystal and Molecular Structure of Triphenylphosphonio Cyanoamide
Triphenylphosphonio cyanoamide Ph3PNCN crystallizes in the monoclinic space group P21/c with a = 957.5 pm, b = 1670.4 pm, c = 1126.7 pm, β = 121.28° and Z = 4. The structure has been determined by Patterson and Fourier techniques and refined by least squares methods to R = 0.047. The most interesting bond lengths and angles are PN = 159.4 pm, PC = 179.9pm (average value), NC = 130.1 pm and 115,1 pm, PNC = 123.0° and NCN = 174.8°. The molecular structure for Ph3PNCN has been compared with those of other iminophosphoranes and discussed with respect to its relation to the series of triphenylphosphine pseudochalcogenides.
TL;DR: In this article, the triorganostannanes were added to vinyl diorganophophosphines to give rise to fragmentation reactions or the formation of organophosphorus substituted tin halides.
Abstract: Die Titelverbindungen 1a–1g werden durch radikalische Addition von Triorganostannanen an Vinyl-diorganophosphine synthetisiert. Ihre Methioiodide 4b–4e unterliegen beim Erhitzen einer heterolytischen Fragmentierung. Die Halogenierung von 1a–1g hangt von den Reaktionsbedingungen ab und fuhrt entweder zu Fragmentierungsreaktionen oder zur Bildung der organophosphorsubstituierten Zinnhalogenide 6a–6e. Die Reaktion von Alkalimetallen mit 1a–1g in flussigem Ammoniak hat in Abhangigkeit von den Substituenten sowohl die Spaltung von Zinn-als auch von Phosphor-Kohlenstoff-Bindungen zur Folge.
Functionally Substituted Organotin Compounds. IV. Synthesis and Reactivity of (2-Di-organophosphinoethyl)triorganostannanes
The title compounds 1a–1g are synthesized by radical addition of triorganostannanes to vinyl diorganophosphines. Their methioiodides 4b–4e undergo by heating a heterolytic fragmentation. The halogenation of 1a–1g depends on the reaction conditions and give rise to fragmentation reactions or the formation of organophosphorus substituted tin halides 6a–6e. The reaction of alkali metals with 1a–1g in liquid ammonia leads to a splitting as well as of tin and phosphorus-carbon bonds depending on the substituents.
TL;DR: Literatur- and Typenstudien an kritischen und wenig bekannten Sippen aus der Xerula-Verwandtschaft fuhrten zu folgenden Ergebnissen, which revealed the following results: Oudemansiella hygrophoroides Singer et Clemencon is regarded as a variety of Xerula radicata.
Abstract: Literatur- und Typenstudien an kritischen und wenig bekannten Sippen aus der Xerula-Verwandtschaft fuhrten zu folgenden Ergebnissen: 1. Oudemansiella brunneomarginata L. Vas. ist nach den Merkmalen der Beschreibungen eine ostasiatische Xerula-Sippe, die mit Collybia radicata ss. Corner (1934) in Beziehung steht. 2. Agaricus ephippium Fries gehort in die Collybia butyracea-Verwandtschaft, nicht zu den Oudemansiellae oder zu den Xerulae. Collybia ephippium ss. Ricken ist nicht mit Agaricus ephippium Fries identisch. 3. Oudemansiella hygrophoroides Singer et Clemencon wird als Varietat von Xerula radicata bewertet. Die Kombination Xerula radicata (Relh. per Fr.) Dorfelt var. hygrophoroides (Singer. et Clemencon) Dorfelt comb. nov. wird vorgenommen. 4. Oudemansiella pseudoradicata Moser ist ein Synonym zu Xerula radicata.
Megacollybia platyphylla (Pers. per Fr.) Kotl. et Pouz. kann weder in der Gattung Xerula Mre. em. Dorfelt noch in der Gattung Oudemansiella Speg. untergebracht werden. Die monotypische Gattung Megacollybia ist durch Huthaut-Struktur, Mycelmerkmale, Rhizomorphae, Sporengrose u. a. Merkmale deutlich von den Gattungen Oudemansiella und Xerula abzutrennen.
Xerula mrlanotricha Dorfelt wurde im Kaukasus nachgewiesen. Das Areal dieser Sippe kann nach Meusel, Jager & Weinert (1964) mit der Formel m/mo — temp/demo · suboz EUR-VORDAS-AFR beschrieben werden.
Neue Funde von Fruchtkorpern der Sektion Albotomentosae (gen. Xerula, subgen. Radicatae) aus Hessen, Baden-Wurttemberg und aus der DDR werden beschrieben. Sie gehoren zu Xerula nigra var. nigra und zu Xerula nigra var. renati.
Studies of critical or poorly known taxa of Xerula, respectively Oudemansiella, revealed the following results: 1. According to the described features, Oudemansiella brunneomarginata L. Vas. is a taxon in eastern Asia which is related to Collybia radicata ss. Corner (1934). 2. Agaricus ephippium Fries belongs to the relationship of Collybia butyracea, but not to Oudemansiella or Xerula. Collybia ephippium ss. Ricken (1915) is not identical with Agaricus ephippium Fries. 3. Oudemansiella hygrophoroides Singer et Clemencon is regarded as a variety of Xerula radicata. The combination Xerula radicata (Relh. per Fr.) Dorfelt var. hygrophoroides (Singer et Clemencon) Dorfelt comb. nov. is introduced. 4. Oudemansiella pseudoradicata Moser is a synonym of Xerula radicata.
Magacollybia platyphylla can be referred neither to the genus Xerula nor to Oudemansiella. This monotypical genus is clearly to be separated from Oudemansiella and Xerula by characteristics of the structure of the scin, mycelium, rhizomorphs, spores and so on.
Xerula melanotricha Dorfelt has been detected in the Caucasus. According to Meusel, Jager & Weinert (1965), the area of this taxon can be described with the formula: m/mo — temp/demo · suboz. EUR-VORDAS-AFR.
TL;DR: Evidence is provided that dietary linoleic acid exerts an effect on the responsiveness of the vessels to vasoactive stimuli and this effect increases the sensitivity to angiotensin II.