Showing papers by "University of Erlangen-Nuremberg published in 1976"
385 citations
TL;DR: In this article, all known ylidreactions of alkylidenetriphenylphosporanes were described, including C-acylations with thiolesters and the ring closure reaction by combined inter-and intramolecular C-alkylation.
Abstract: Das in vielen organischen Losungsmitteln gut losliche Natrium-bis(trimethylsily)amid (2) eignet sich ausgezeichnet als Base zur darstellung lithiumsalzfreier Alkylidentriphenylphosphoran-Losungen, die fur alle bekannten Ylidreaktionen eingesetzt werden konnen. Als Beispiele solcher Reaktionen werden die cis-stereoselektive Witting-Reaktion, die C-Acylierung mit Thiolestern und die Ringschlusreaktion durch kombinierte inter-und intramolekulare C-Alkylierung beschrieben.
Reactions of Alkylidenetriphenylphosporanes, XXXIII. Preparations of Lithiumsaltfree Ylidsolutions with Sodium bis (trimethylsily)amide as Base
Sodium bis(trimethylsilyl)amide (2) which is soluble in many organic solvents is a very useful base for the generation of lithiumsaltfree solutions of alkylidenetriphenylphosphoranes. With these solutions all known ylidreactions can be carried out. cis-Stereoselective Wittig reactions, C-acylations with thiolesters and the ring closure reaction by combined inter-and intramolecular C-alkylation are described.
213 citations
TL;DR: In this article, the quadrupole hyperfine interaction of Ga, In, Sn, and of 67Zn, 69Ge in Zn was measured with high accuracy using TDPAC and TDPAD methods.
Abstract: The quadrupole hyperfine interaction of111Cd in Cd, In, Sn, and of67Zn,69Ge in Zn was measured with high accuracy using TDPAC and TDPAD methods; in addition the systems117In in Cd and In, and113Sn in Cd were investigated. The temperature dependence of the electric field gradienteq(T) can be reproduced by the simple relationeq(T)/eq(0)=1—B⋅T
3/2 over a range of temperatures from a few K up to the melting point. A comparison with other experiments was carried out to test the universality of this empirical relation. In particular, high precision NQR experiments on Ga, In and Sb strongly support this relation. It is discussed whether lattice vibrations can explain the observed temperature variation or whether the experimental data indicate the need for a new description. Some new ideas suggesting a basically different model are given.
173 citations
TL;DR: In this article, secondary ion mass spectroscopy (SIMS) was used to investigate the adsorption energy of water on (001) cleavage planes of LiF, NaF and NaCl.
163 citations
TL;DR: Reinfection by spontaneously released virus may explain the sudden increase in EBNA‐positive BJAB cells and two distinct patterns of EBNA staining in P3HR‐1 virus‐infected cells were observed, suggesting a genetic heterogeneity of this virus preparation.
Abstract: Cells of two EBNA (Epstein-Barr virus nuclear antigen)-negative human lymphoma cell lines, BJAB and RAMOS, were infected with two strains of Epstein-Barr virus (EBV). In two different experiments, B95-8 virus-infected BJAB cells revealed a gradually increasing number of EBNA-positive cells. Twenty weeks after infection almost 100% of the cell population expressed this antigen. In contrast, it has not so far been possible to convert RAMOS cells into an EBNA-positive cell line. The initial proportion of 35% EBNA-positive cells declined to about 10% 20 weeks after infection. The development of EBNA-positive multinuclear giant cells was a characteristic feature of infection with B95-8 virus. EA (early antigen) and VCA (virus capsid antigen) appeared in less than 0.1% of the cell population after induction with IUdR only. Infection of BJAB and RAMOS cells with P3HR-1 virus finally resulted in both cases in EBNA-positive lines. In contrast to B95-8 virus, the number of EBNA-positive lines. In contrast to B95-8 virus, the number of EBNA-positive cells remained below 1% during the first 6 to 8 weeks. A sudden increase occurred thereafter, bringing the number of EBNA-expressing cells to almost 100% within the following 4 weeks. During this period, BJAB but not RAMOS cells revealed a small number of EA- as well as VCA-positive cells (less than 0.1%). Thus, reinfection by spontaneously released virus may explain the sudden increase in EBNA-positive BJAB cells. Two distinct patterns of EBNA staining in P3HR-1 virus-infected cells were observed. They may suggest a genetic heterogeneity of this virus preparation.
142 citations
TL;DR: The molecular weight of three preparations of human papilloma virus DNA derived from different plantar warts was determined by agarose gel electrophoresis or electron microscopic contour length measurement and two of the three DNA preparations revealed an identical cleavage pattern.
Abstract: The molecular weight of three preparations of human papilloma virus DNA derived from different plantar warts was determined by agarose gel electrophoresis or electron microscopic contour length measurement. It was found to amount to approximately 4.9 X 10(6). Analysis of this DNA after sequential digestion by four different restriction endonucleases (EcoRI, Bam, Hind II, and Hind III) permitted physical mapping of the cleavage sites. Two of the three DNA preparations revealed an identical cleavage pattern, whereas the third one contained two additional cleavage sites.
126 citations
TL;DR: In this article, a theorem dealing with interesting properties of a polynomial D(z), being the denominator of the transfer function of a stable discrete system, is presented and proven.
Abstract: A theorem is presented and proven, dealing with interesting properties of a polynomial D(z), being the denominator of the transfer function of a stable discrete system. The relationships to equivalent properties of a Hurwitz polynomial are considered.
123 citations
TL;DR: In this article, the emission spectrum of ZnO crystals in the band edge region was investigated and it was shown that the emission lines at λ = 3696.58 A and λ= 3692.66 A are due to an exciton bound to a neutral Li and Na acceptor, respectively.
111 citations
TL;DR: Tumour biopsies from Burkitt lymphoma patients, as well as human nasopharyngeal carcinoma cells growing in athymic nude mice, contain Epstein–Barr virus DNA as covalently closed circular DNA.
Abstract: Tumour biopsies from Burkitt lymphoma patients, as well as human nasopharyngeal carcinoma cells growing in athymic nude mice, contain Epstein–Barr virus DNA as covalently closed circular DNA. In addition, integrated viral DNA sequences seem to be present.
110 citations
TL;DR: Triacetyl cellulose obtained by heterogeneous acetylation of cellulose shows a laminated arrangement within these sections which is similar in uniformity to a crystal lattice as discussed by the authors.
105 citations
TL;DR: Endoscopically controlled laser beam coagulation has since been applied successfully in the treatment of hemangiomas, angiodysplasia, intestinal angiomatosis, bleeding gastric erosions, bleeding gastrointestinal ulcers, and iatrogenic hemorrhage in the stomach following big particle biopsy in 94 lesions.
TL;DR: Endoscopists are well advised to be familiar with the ontogenic variants in the pancreas and its duct system, including the anomaly of "pancreas divisum" that can be marked by isolated pancreatitis.
TL;DR: In this paper, the steady state values of the dislocation density in the subgrain interior (ρi) and of the sub-grain size were determined by means of transmission electron microscopy.
TL;DR: Various biopsies from different European malignant lymphomas, two biopsie from nasopha‐ryngeal carcinomas, and material from non‐neoplastic lymph nodes were assayed for the presence of Epstein‐Barr virus (EBV) DNA by nucleic acid hybridization.
Abstract: Various biopsies from different European malignant lymphomas, two biopsies from nasopha-ryngeal carcinomas, and material from non-neoplastic lymph nodes were assayed for the presence of Epstein-Barr virus (EBV) DNA by nucleic acid hybridization. Reassociation kinetics of in vitro-labelled EBV DNA were studied in the presence of tumor DNA. The lymphomas tested included among others follicular lymphomas, germinocytomas, immunoblastic lymphomas and lymphoplasmacytoid immunocytomas. Epstein-Barr viral DNA was demonstrated within the two nasopharyngeal carcinoma biopsies as expected. A histologically typical Burkitt lymphoma as well as an immunoblastic lymphadenopathy with excessive plasmacytosis also contained EBV-DNA. The Burkitt biopsy revealed about 15 EBV genome equivalents per cell. Antibodies against EBV-specific antigens were highly elevated in the serum of this patient. The material of the patient with immunoblastic lymphadenopathy contained 2-3 EBV genome equivalents per cell.
TL;DR: In this article, the authors used the dissociative sublimation of SnO2 in SnO and O2 supported by H2 and reoxidation of the transported SnO.
TL;DR: According to biochemical and physiological characters, 77 strains of Chlorella were assigned to 12 taxa and certain nutritional characters were found to be more or less strain-specific, highly variable, and therefore unsuitable for taxonomy.
Abstract: According to biochemical and physiological characters, 77 strains ofChlorella were assigned to 12 taxa. The characters used are presence or absence of hydrogenase, formation of secondary carotenoids under nitrogen-deficient conditions, liquefaction of gelatin, products of glucose fermentation, ability to reduce nitrate, thiamine requirement, acid tolerance, salt tolerance, thermophily, and base composition of DNA (GC content). On the other hand, certain nutritional characters, i. e., utilization of organic carbon and nitrogen compounds, were found to be more or less strain-specific, highly variable, and therefore unsuitable for taxonomy.
TL;DR: The mikrokristalline acetylcellulose organische Molekule as mentioned in this paper is a stoffspezifisch stoff-spezialisation of the kristallinen acetylieren, das die Konformation and die gegenseitige Anordnung der Kohlehydratbander in ihren kristalinen Bereichen erhalten bleibt.
Abstract: Cellulose last sich in der Weise acetylieren, das die Konformation und die gegenseitige Anordnung der Kohlehydratbander in ihren kristallinen Bereichen erhalten bleibt. In gequollenem Zustand includiert diese mikrokristalline Acetylcellulose organische Molekule der verschiedensten Art stoffspezifisch und es lassen sich daran chromatographische Trennungen durchfuhren. Chirale Verbindungen werden dabei teilweise, in einigen Fallen vollstandig in die Antipoden gespalten. Diese Fahigkeiten verschwinden weitgehend, wenn das Material aus organischen Losungen umgefallt wird. Eine besonders hohe Affinitat zu der mikrokristallinen Acetylcellulose hat der Benzolkern, wenn mindestens 3 benachbarte Stellen nicht substituiert sind. Die Haftfestigkeit wird viel starker durch sterische Faktoren als durch die chemische Natur der Substituenten beeinflust. Insbesondere lassen sich o-Disubstitutionsprodukte des Benzols praparativ von den m- und p-Isomeren trennen. Da die neue Methode besonders gut auf Kohlenwasserstoffe und andere unpolare Molekule anspricht, erganzt sie die Gas-Chromatographie bei der Trennung und Reinigung labiler Verbindungen.
TL;DR: In seven healthy volunteers pure pancreatic juice was obtained by endoscopic cannulation of the papilla of Vater and the effect of increasing secretin doses on bicarbonate and cyclic AMP concentrations was remarkably similar, suggesting the participation of cyclicAMP in human pancreatic bICarbonate secretion.
TL;DR: Estimates show that natural radionuclides in phosphate fertilizers contribute but very little to the mean terrestrial radiation exposure of the population which is 50 to 55 mrd/a in Germany and a significant increase of the external radiation exposure has to be expected which could reach a doubling of the mean natural exposure value.
Abstract: The natural radionuclide content of mineral phosphate fertilizers has been determined gammaspectrometrically. The investigations comprised ca. 70% of the mineral phosphate fertilizers authorized and used in the Federal Republic of Germany (FRG). At maximum, we found specific activities of 62 nCi Unat/kg, 23 nCi226Ra/kg, 1.6 nCi Thnat/kg and 262 nCi40K/kg. The mean values, weighted by the percentual agricultural consumption of the main phosphate fertilizer groups in 1973/74 and related to the phosphate content, amounted to 58, 40, 2, and 584 nCi/kg P2O5 for Unat,226Ra, Thnat, and40K respectively. This resulted in an annual distribution due to phosphate fertilizing of about 3.9 µCi Unat, 2.7 µCi226Ra, 0.1 µCi Thnat, and 39.9 µCi40K per ha of arable or pasture land in 1973/74 on the average. From these values the air dose rates over agricultural areas have been estimated under extreme conservative assumptions resulting in an additional external exposure of members of the population of 0.02 mrd/a on the average and 0.4 mrd/a in the region of highest phosphate fertilizing intensity. If it is assumed that radium contained in phosphate fertilizers were completely accumulated in the soils during the last 80 years, this value would be raised to 0.3 mrd/a on the average. The occupational external radiation exposure due to natural radionuclides contained in phosphate fertilizers was estimated to be 0.1 mrd/a on the average and 2.3 mrd/a at maximum for persons working in agriculture. These estimates show that natural radionuclides in phosphate fertilizers contribute but very little to the mean terrestrial radiation exposure of the population which is 50 to 55 mrd/a in Germany. Only for the small group of persons working in fertilizer production plants or storehouses a significant increase of the external radiation exposure has to be expected which could reach a doubling of the mean natural exposure value.
TL;DR: The physiological stimulus leading to motilin release in man has not yet been determined as mentioned in this paper, however, it has been shown that motilins after duodenal acidification may be an important factor in inhibiting gastric emptying.
TL;DR: It is proved that the backbone of the principal lysobisphosphatidic acid from all three sources has the structure of 1-sn-glycerophospho-1- sn- glycerol.
TL;DR: The results show that for the dilatation of the cervical canal during labour biochemical changes must take place not only in the ground substance, but also in the collagenfibres.
Abstract: The solubility of collagen during pregnancy and labour was studied in tissue specimens of the uterine cervix of 48 women in childbearing age. In the course of pregnancy the fractions of collagen which are soluble in 0.175 M acetic acid at +4° C and in 8 M urea at +40° C increased continuously in relation to the total collagen content and dry weight. The highest values are found during labour at full cervical dilatation and also immediately post partum. The results show that for the dilatation of the cervical canal during labour biochemical changes must take place not only in the ground substance, but also in the collagenfibres.
TL;DR: In this article, stress reduction tests were performed during steady state tensile creep of Al-11 wt.% Zn at 523 K and constant stresses between 10 and 30 MPa.
TL;DR: The solvolysis of phenyl triflate (3), phenyl non-aflate (4), o-methylphenyl nonaflate, o-methoxyphenyl (M), 2,6-dimethoxymythoxymethylphenyl (S), 2.6-diisopropylphenyl iflate (2.6), 3,5-dimethylcyclopropyl (3.5-dicyclopyropyl)phenyl triferlate, 2.4-6-triisophropyl
Abstract: The solvolysis of phenyl triflate (3), phenyl nonaflate (4), o-methylphenyl nonaflate (5), o-cyclopropylphenyl nonaflate (6), o-methoxyphenyl triflate (7), 2,6-dimethoxyphenyl triflate (S), 2,6-diisopropylphenyl triflate (9), 33- dimethoxyphenyl triflate (lo), 3,5-dicyclopropylphenyl triflate (11), 3,5-di(2-methylcyclopropyl)phenyl triflate (12), 2,4,6-tricyclopropylphenyltr iflate (13), and 2,4,6-triisopropylphenytlr iflate (14) were examined in great detail under a wide variety of conditions. In highly polar nonnucleophilic solvents no reaction was observed and the unreacted triflates were recovered quantitatively. In the presence of nucleophiles or nucleophilic solvents the sole products observed were the corresponding phenols. Careful labeling and product studies showed that these phenols arose by nucleophilic attack on sulfur and S-0 bond cleavage. We have not been able to find any evidence for aryl cation intermediates.
TL;DR: In this paper, a whole summer continuous measurements of temperature (°C), light intensity (lux) and spectral composition of the light (colour temperature in °K) were done in Spitsbergen (78° N) to find out which of daily oscillating environmental factors in the continuous daylight of arctic summer are responsible for synchronization of animal activity period with the rotation of the earth.
Abstract: To find out which of daily oscillating environmental factors in the continuous daylight of arctic summer are responsable for synchronization of animal activity period with the rotation of the earth, in Spitsbergen (78° N) a whole summer continuous measurements of temperature (°C), light intensity (lux) and spectral composition of the light (colour temperature in °K) were done. With a daily amplitude of 4-5° C in the air, resp. 10° C at the ground surface, temperature can only act as a Zeitgeber for heterothermic animals. Measurements of light intensity (with a photocell directed vertical upward to the zenith) showed relatively large daily oscillations. But since light intensity depends on the cosine of the angle of incidence of the light (Lambert's cosine law) and in high latitudes the angle of incidence of the sun is always very great, in fact measurements have to be done with the photocell directed to the sun or, as the latter meets with mechanical problems, all dates got with the photocell vertical upward must be converted after Lambert's cosine law. Converted dates of light intensity oscillate not nearly as intense as measured dates. This small daily amplitude of light intensity, which in addition is strongly influenced by sudden changes of the wheather, can hardly come into consideration as a Zeitgeber of animal activity period. Colour temperature however showed large and regular daily oscillations and therefore could be a Zeitgeber of animal activity period in high arctic summer, particularly because in the laboratory the synchroniing effect of an artificial daily alternation of colour temperature is already proved. Nest (feeding) activity of local snowbuntings and perch hopping activity of greenfinches, brought from Germany, were registrated with light traps. Activity period of both bird species was clearly synchronized with the rotation of the earth. In a narrow valley the activity pattern of greenfinches was identical as in open country, in spite of temporarily total other conditions of light intensity (shading by mountains). Apparently even the activity period of non arctic animals can be synchronized by weak Zeitgebers like colour temperature.
TL;DR: In this article, a standard television system in combination with a processing computer is used for measurements of LEED beam intensities of a spot pattern, which can be integrated for one selected spot by the computer which also takes care of automatic background subtraction.
Abstract: A standard television system in combination with a processing computer is used for measurements of LEED beam intensities of a spot pattern. The video signal of the TV camera contains the intensity distribution of each spot. This can be integrated for one selected spot by the computer which also takes care of automatic background subtraction. The processing program controls the energy of the incident electron beam and follows the moving spot position. One integration of a profile and thus the measurement of one point of anI(E) curve takes 0.5 s or less. Diffracted beam currents down to 10−11 A can be detected with the present experimental set-up. The output is immediately displayed and recorded in final reduced formI/I
0.
TL;DR: In this paper, the analysis of the differential cross section and analyzing power for 3 H(p, p) 3 H has been carried out at 21 bombarding energies between 4.5 and 12 MeV. The results of this analysis are compared with those of other analyses, with theoretical predictions, with respect to the level structure of 4 He.
01 Jan 1976
TL;DR: This chapter presents some physiological evidence and thoughts on localized responses, intracellular localization, and action of phy tochrome, and outlines several ways to demonstrate phytochrome being bound to membranes.
Abstract: This chapter presents some physiological evidence and thoughts on localized responses, intracellular localization, and action of phytochrome. It outlines several ways to demonstrate phytochrome being bound to membranes. There are systems and responses where spatial differences in the state of phytochrome within a single cell result in a localized response. Moreover, there are two types of systems and responses, that is, phototropism in the filamentous gametophyte of ferns and mosses (the so-called protonema) and the orientation movement of the chloroplast in the green alga Mougeotia . The cylindrical cell of Mougeotia is unique in its structure, having a single flat chloroplast that divides the cell into two half-cylinders and is able to turn in response to the direction of light. When unilateral red light is applied to Mougeotia , the chloroplast turns so as to show its face to the light. This response can occur in complete darkness after a short red induction, and this induction is far-red reversible. By irradiating small areas of a cell with micro-beams of red light, it was found that to be orientated by the light, the chloroplast itself does not need to be hit by the light. Thus, phytochrome is localized outside the chloroplast.
TL;DR: It is concluded that both these organelles contribute to the periodic shading of Volvox, and the phototactic action spectrum is assumed to represent the absorption of the photoreceptor pigment and that of the shading pigment(s) in a complex way.