showing 36 of ~574560 from 574555 documents
Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 3. Poly-β-propiolacton, poly-β-pivalolacton und poly-δ-valerolacton
1978
Poly(oxycarbonylethylene) (poly-β-propiolactone), poly(oxycarbonyl-1,1-dimeothylethylene) (poly-β-pivalolactone), and poly(oxycarbonyltetramethylene) (poly-δ-valerolactone) were pyrolyzed directly in the ion source of a mass spectrometer and their thermal and electron impact induced degradation mechanisms are established. Poly-β-propiolactone is thermally degraded by rupture of the OCH2-bond by a cis elimination to give carboxyl and acryloyl endgroups, whereas poly-δ-valerolactone depolymerizes to δ-valerolactone. Poly-β-pivalolactone degrades thermally to cyclic oligomers of pivalolactone, which could be proved by a separated pyrolysis and IR-spectroscopy and gel chromatography.
Magnetic hyperfine spectrum of isolated (199Hg)+ Ions
1978
The (199Hg)+ ions were stored in an RF quadrupole electric field and their ground state hyperfine populations pumped optically using the ion resonance radiation at 1942 A from a (202Hg) isotope enriched lamp. A microwave field at 40.5 GHz was phase-locked to the 1350th harmonic of the output of a frequency synthesizer, referenced to a Cs-beam frequency standard. Using a digital averager, a high background suppression optical system monitored the fluorescence light from the ions. Linewidths on the order of 3 Hz were observed for the “field-independent” 0-0 transition, and a value of 40, 507, 348, 051±50 Hz was deduced for the magnetic hyperfine interval, corrected to zero magnetic field.
GENETIC AND PHYSIOLOGICAL STUDIES OF THE EFFECT OF LIGHT ON THE DEVELOPMENT OF THE MOSS, PHYSCOMITRELLA PATENS
1978
Abstract The germination of Physcomitrella patens spores only occurs when wet spores are exposed to light. Depending on their ripeness, spores require from 44 to 64 h illumination to bring about maximum germination. There is a lag period of about 15 h between the reception of sufficient light to elicit germination before germination can be observed. Wavelengths in the range 640-680 nm are much more effective in inducing germination than longer or shorter wavelengths, but far-red reversal of red light induction of germination has not been demonstrated. Light also has very marked effects on protonemal and gametophore development. In darkness, only caulonemata are produced, and these grow nega…
Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 4. Polyester und copolyester der milchsäure und glykolsäure
1978
Polyesters and copolyesters of 2-hydroxyacetic acid (glycolic acid) and 2-hydroxypropionic acid (lactic acid) were investigated by direct pyrolysis in the ion source of a mass spectrometer. Thermal degradation of these polyesters and copolyesters at 10−6 mbar yields cyclic oligomers which are further degraded by an electron impact induced mechanism by elimination of formaldehyde or acetaldehyde and CO2 to give characteristic series of linear ions. In the pyrolysis mass spectrum of a copolyester (mole ratio of monomeric units ≈1:1) intact sequences up to 8 monomeric units can be observed.
Muonic isotope shifts in the stable Ca nuclei
1978
Abstract Precise isotope shifts of the 2p-1s muonic transition energies for the stable Ca isotopes have been measured. Model-independent radius differences are derived from combined analysis of the present data and elastic electron scattering data. The precise new 48−40 Ca isotope shift disagrees with Hartree-Fock predictions.
Bacterial 2,3-butanediol dehydrogenases
1978
Enterobacter aerogenes, Aeromonas hydrophila, Serratia marcescens and Staphylococcus aureus possessing L(+)-butanediol dehydrogenase produced mainly meso-butanediol and small amounts of optically active butanediol; Acetobacter suboxydans, Bacillus polymyxa and Erwinia carotovora containing D(-)-butanediol dehydrogenase produced more optically active butanediol than meso-butanediol. Resting and growing cells of these organisms oxidezed only one enantiomer of racemic butanediol. The D(-)-butanediol dehydrogenase from Bacillus polymyxa was partially purified (30-fold) with a specific activity of 24.5. Except NAD and NADH no other cofactors were required. Optimum pH-values for oxidation and red…
CONTRIBUTO CLINICO AI TUMORI RETROPERITONEALI IN ETA' PEDIATRICA
1978
Gli Autori descrivono un caso di neurofibroma retroperitoneale recidivante a partenza dalla capsula renale, occorso alla loro osservazione. Viene descritto l'iter diagnostico-terapeutico
Untersuchungen zum oxidativen abbau nativer cellulose, 4. Stöchiometrische verhältnisse zwischen der anzahl der entstehenden spaltstellen, dem sauers…
1978
An investigation of the kinetics of cellulose degradation confirms the scheme proposed by G. V. Schulz and Mertes with the following modifications: the fast pre-stage of the degradation is missing, because there are no faster cleaving bonds in the native cellulose; the first step of the degradation (pre-oxidation) in agreement with the above mentioned authors consists in the uptake of an oxygen atom: in the second step, the scisson proper, the scheme of Staudinger and Roos is replaced by the newer and better founded scheme of Haskins and Hogsed, assuming an alkoxy-elimination; the third step (post-oxidation) finally consists in a limited number of substeps leading to a splitting off of abou…
Inhibitoren der Korrosion 21 (1) - Autoxidationsstudien an Fe2+-Salzen der Tetramethylen-1,4-bis-phosphonsäure, der Hexamethylen-1,6-bis-phosphonsäur…
1978
Die Wirksamkeit der organischen Bisphosphonsauren als Inhibitoren der Korrosion von Eisen ist dadurch bedingt, das die aus der Eisenoberflache auftretenden Fe2+-Ionen direkt am Austrittsort mit den Sauren reagieren und an Ort und Stelle dreidimensional vernetzte Deckschichten aufbauen. Je dichter die Struktur dieser Schichten, je bestandiger das Netzwerk gegen Sauerstoff und je hydrolysebestandiger die FeOP-Bindungen, desto besser ist die Schutzwirkung: Dadurch wird sowohl dem Sauerstoff als auch dem Chloridion der Zugang zur Metalloberflache verwehrt. Die Modellversuche ermoglichen aufgrund der Verteilung des Phosphors in den Niederschlagen Ruckschlusse auf den Vernetzungsgrad. Corrosion I…
Herstellung und 13 C‐NMR‐Spektroskopie isomerer 1,4‐Heterophosphorinanium‐Salze
1978
Die quartaren Diallylphosphonium-Salze 1–8 werden mit Natronlauge, Natriumhyrogensulfid. Ammoniak oder prim. Aminen zu den 1,4-Oxa- (9–14), 1,4-Thia- (15–21) und 1,4-Azaphosphorinanium-Salzen (22–36) umgesetzt. Die Konformation bzw. Konfiguration der in den meisten Fallen als Isomerengemische anfallenden Salze 9–36 wird 1H- bzw. 13C-NMR-spektroskopisch untersucht. Eine Abhangigkeit von der geometrischen Anordnung sowohl der 4JPH- als auch der vicinalen3JPC-Kopplungskonstanten konnte bei diesen nicht gespannten 1,4-Diheterocylohexanen festgestellt werden. Synthesis and 13C NMR Spectra of Isomeric 1,4-Heterophosphorinanium Salts The phosphonium salts 1–8 react with aqueous sodium hydroxide, s…
Studien zum Vorgang der Wasserstoffübertragung, 49: Zur Frage der Auslösung einer optischen Induktion durch Anwendung optisch aktiver Ephedrinderivat…
1978
Die quartaren Ephedriniumsalze 1–5 sowie die bekannten Kronenether 6 und 7 werden als Leitsalze bei der Elektroreduktion von Acetophenon eingesetzt. Hierbei wird das Produktverhaltnis: sekundarer Alkohol (A) zum Diol (B) sowie die optische Induktion von A wesentlich durch das Leitsalz beeinflust. Es wird hieraus der Schlus gezogen, das weniger die Elektrosorption der Leitsalze an die Quecksilberoberflache als vielmehr feldbedingte Orientierungs- und Assoziations-phanomene zwischen optisch aktivem Leitsalz und prochiralem Substrat im diffusen Bereich der elektrochemischen Doppelschicht wirksam sind. Studies on the Occurrence of Hydrogen Transfer, 49: On the Optical Induction Produced in the …
Bromocriptine and Prostatic Carcinoma: Plasma Kinetics, production and Tissue Uptake of3H-Testosterone in Vivo
1978
The influence of the anti-prolactin bromocriptine on plasma kinetics, production rate and tissue uptake of testosterone was investigated in 15 patients with newly diagnosed stages C and D prostatic carcinoma. Bromocriptine was given for 5 days in a daily dose of 15 mg. orally. The studies were performed with the single injection technique using the 2-compartment model. Plasma testosterone, serum prolactin, and luteinizing and follicle-stimulating hormones were determined initially. Blood samples were drawn up to 5 hours after the injection of 3H-testosterone. For tissue studies a transrectal needle biopsy was done 3 hours post-injection. Bromocriptine suppressed prolactin and the endogenous…
Comparative study of the performance of spherical and angular silica and alumina supports in the 1-10-μm size range
1978
Summary Columns packed with four different sets of well characterized packings, spherical silica, angular silica, spherical alumina and angular alumina, varying in mean particle diameter ( d p ) between 1 and 10 μm, were compared. On these columns, the chromatographic permeability ( K 10 ), the column resistance parameter (Φ) and the reduced plate height-velocity dependences were determined under identical and comparable conditions. Discrepancies were found for K 10 and Φ depending on the type of packing and the particle shape. The courses of the h versus v plot, however, were nearly identical for packings with d p > 4 μm, showing a minimum at v ≅ 5 and h = 1.5–2.5 for solutes of k ′ ≅ 0.2 …
The Effect of Nitrazepam on Manual Skill, Grip Strength, and Reaction Time with Special Reference to Subjective Evaluation of Effects on Sleep
1978
The effects of 5 and 10 mg oral nitrazepam doses on manual skills, grip strength, and reaction time 8 hours after ingestion of the drugs were studied in 34 healthy female volunteers aged 19-22 years. 5 mg nitrazepam caused a slight but insignificant decrease in psychomotor skills. With 10 mg psychomotor skills were influenced significantly. Grip strength and reaction time were not influenced either by the 5 or 10 mg doses. The investigators corroborate the value of the established effects of nitrazepam as a hypnotic, but recommend that caution should be excercised in prescribing the drug as a hypnotic (especially in doses exceeding 5 mg) to work-aged subjects as there is a risk of significa…
On-line Mössbauer measurements at low temperatures of 83mKr implanted into Al
1978
Abstract A vacuum ion implantation chamber housing a helium flow cryostat and a Mossbauer transducer has been constructed and coupled directly to an ion separator for low temperature implantation and on-line Mossbauer measurements. 83m Kr, produced by thermal neutron activation of enriched 82 Kr gas, has been implanted into Al foils in the temperature range 15–300 K. Annealing effects and the temperature dependence of the Lamb-Mossbauer factor have been studied by Mossbauer measurements (at 15–35 K) using the implanted Al targets as sources and Kr/hydrochinone as absorber.
Die Flavonoide von Riccia fluitans L.
1978
Summary Five flavonoids of Riccia fluitans were analysed by means of paper chromatography and uv-spectral data. One substance was identified as luteolin, the others are glycosides of apigenin and luteolin: apigenin-7-O-glucuronide, luteolin-7-O-glucuronide, luteolin-7-O-glucuronide-3’-O-rhamnoside and luteolin-6,8-di-C-glycoside (lucenin).
Darstellung und spektroskopische Analyse von Oligo{[4-(1,1,3,3-tetramethylbutyl) (bzw. 4-octyl)2-hydroxy-1,3-phenylen]methylen}en und ihrer Ausgangsv…
1978
4-(1,1,3,3-Tetramethylbutyl)phenol und 4-Octylphenol, erhalten durch Friessche Verschiebung der entsprechenden Phenylester und anschliesende Reduktion der Carbonylgruppe, wurden in ortho-Stellung monobromiert und mit Formaldehyd hydroxymethyliert. Aus diesen Verbindungen konnten sechs 2,2′-Methylendiphenole (2a–f) sowie sieben 2,6-Bis(2-hydroxybenzyl)phenole (3a–g) dargestellt werden, die in 4-Stellung zu den phenolischen Hydroxygruppen Methyl-, 1,1,3,3-Tetramethylbutyl- und Octyl-Substituenten in verschiedenen Verhaltnissen enthalten. Die IR- und 1H-NMR-spektroskpischen Analysen bestatigten die angegebenen Strukturen der dargestellten phenolischen Mehrkernverbindungen. 4-(1,1,3,3-Tetrameth…
Search for High-Spin Isomers in 150Dy
1978
A search for yrast traps in 150Dy has been made by studying the γ-ray decay following the 144Nd (12C, 6n) 150Dy and 146Nd (12C, 8n) reactions. Although an average value of about 30 units of angular momentum is imparted to the final nucleus using these reactions, no evidence is found for the existence of isomers with half-lives longer than 10 ns.
Structure and properties ofn-alkyldimethylsilyl bonded silica reversed-phase packings
1978
Summary The effects of the modifier functionality and the chain length ofn-alkylchlorosilanes on the surface structure of packings and on their retention behaviour in reversed-phase chromatography were investigated. Comparative retention studies on three silica packings that had been treated to maximum conversion withn-octyltrichlorosilane (I),n-octylmethyldichlorosilane (II) andn-octyldimethylmonochlorosilane (III) showed that the most pronounced reversed-phase character is obtained by using III as the modifying reagent. A series ofn-alkyldimethylsilyl bonded silica packings were prepared with widely differingn-alkyl chain lengths. Although the packings are very hydrophobic, the maximum su…
Characterization of the Proteinases Present in Germinating Seeds of Scots Pine, Pinus sylvestris
1978
Methods were developed to determine proteinase activity in germinating seeds of Scots pine. The assays were based on the liberation of TCA-soluble peptides from haemoglobin at pH 3.7 and from casein at pH 5.4 and pH 7.0; the reaction products were determined by the Lowry method. — Endosperms separated from seeds at the time of rapid storage protein mobilization (seedling length between 20 and 50 mm) showed high proteinase activities in all three assays. Experiments with different inhibitors suggested that at least four enzymes were involved. One of the enzymes resembled mammalian and microbial pepsin-like acid proteinases: the pH optimum was 3.7 and the enzyme was inhibited by pepstatin.—Th…
Über die Verbreitung von Flavonoiden bei akrokarpen Laubmoosen
1978
Summary The methanolic extract from the sporophytes of the moss Ceratodon purpureus (L.) Brid . (Ditrichaceae) contains one flavonoid. It was isolated and purified by means of paper chromatography and identified by cochromatography with authentic material and by UV-spectral data as luteolin. No glycosides of either luteolin or another flavonoid could be detected.
Experimental study on the free transplantation of mucosa and lyophilised dura to the oral cavity
1978
Summary The covering of epithelial defects in the oral cavity presents special problems in preprosthetic surgery, since special requisites for function and quality of mucosal grafts must be satisfied. In animal experiments mucosal defects in the oral cavity of 30 rabbits were repaired with free transplants of autologous mucosa and heterologous lyophilised dura. A comparative clinical and histological assessment of the healing processes showed that there was no essential difference between both methods. Considering the necessary second intervention, the infliction of a second wound, as well as the limited source of mucosa, our results show that the use of lyophilised dura in preprosthetic su…
Monomere und polymere Succinimidoester von ω-Methacryloylaminosäuren, ihre Darstellung und ihre Reaktion mit Aminen
1978
Mit der in dieser Arbeit beschriebenen Synthese von ω-Methacryloylaminosaure-succinimidoestern (1) wurden Monomere erhalten, die leicht mit Methacrylamid copolymerisiert werden konnten. Die entstandenen Copolymeren, die als Trager fur Enzyme und Pharmaka verwendet werden konnen, tragen die selektiv mit Aminen reagierende Succinimidoester-Gruppe an einem “Spacerarm”. Die Reaktionsfahigkeit der neuen Monomeren gegenuber verschiedenen Aminen wurde untersucht. The synthesis of succinimido esters of ω-methacryloylaminocarboxylic acids affords monomers which can easily be copolymerized with methacrylamide. The resulting copolymers have a succinimido ester group fixed on a “spacer arm”, which reac…
Platelet Activation: a New Biological Activity of Guinea-pig C3a Anaphylatoxin
1978
3H-serotonin-release from labelled gp-platelets is established as a sensitive method for testing a new biological activity of gp-C3a anaphylatoxin in an autologous situation. Time-, dose- and temperature-dependent release reactions as well as specific inhibition by carboxypeptidase B and anti-C3a antibodies show that C3a is a potent and specific inducer of platelet activation. Inactive C3a does not induce 3H-serotonin-release but specifically inhibits the action of C3a on platelets.
Darstellung einiger oligomerer Cyclo{oligo[(2-hydroxy-1,3-phenylen)methylen]}e. Spektroskopische Untersuchung ihrer Pseudorotation
1978
Es wird die Darstellung von Cyclo{tris[(2-hydroxy-5-methyl-1,3-phenylen)methylen]-(2-hydroxy-5-tert-butyl-1,3-phenylen)methylen} (4a), Cyclo{bis[(2-hydroxy-5-methyl-1,3-phenylen)methylen]-bis[(2-hydroxy-5-tert-butyl-1,3-phenylen)methylen]}(4b) und Cyclo-{pentakis[(2-hydroxy-5-methyl-1,3-phenylen)methylen]} (4c) beschrieben. Die IR-Spektren zeigen, das die phenolischen Hydroxygruppen der Vierringverbindungen 4a und 4b intramolekulare, vom Losungs(CCl4)- oder Zerteilungsmittel (KBr) weitgehend unabhangige Wasserstoffbrucken bilden, die bei der pentameren Ringverbindung 4c schwacher sind. Anhand der 1H-NMR-Spektren last sich bei diesen Verbindungen eine Pseudorotation nachweisen. Die Massenspe…
Search for quarks in proton-proton interactions at √s = 52.5 GeV
1978
The results of an experiment to search for quarks in pp collisions, at a total centre-of-mass energy √s = 52.5 GeV, are reported. The experiment was sensitive to fractionally charged particles with 0.035e ⩽ |Q| ⩽ 0.67e,β =v/c ⩾ 0.1, and masses up to 21 GeV/c2. The 90% confidence level on the ratio «quark flux/charged-particle flux» is 5.11 · 10−11 for |Q| = 1/3e. This value holds true for particles produced with a mean transverse momentum of 0.4 GeV/c.
A novel haemoprotein induced by isosafrole pretreatment in the rat
1978
Abstract Sodium dodecyl sulphate-polyacrylamide gel electrophoresis has been used to demonstrate that pretreatment of rats with isosafrole results in the formation of a novel species of cytochrome P-450 (mol. wt. 54,000) quite distinct from that induced by phenobarbitone pretreatment (mol. wt. 50,000) or 3-methylcholanthrene (mol. wt. 58,000).
Instrumentation und Nachweisvermögen oberwellenpolarographischer Analysenverfahren
1978
Der Einflus der Instrumentation der einzelnen Baugruppen eines Oberwellenpolarographen auf das Nachweisvermogen der Gesamtmeseinrichtung wird untersucht. Der Gesamtaufbau eines solchen Polarographen wird beschrieben.
Zusammenfassung der Diskussion zum Thema: „Theoretische Grundlagen der Lokalanästhesie“
1978
A New Method for Measuring the Oxygen Content in Microliter Samples of Gases and Liquids: The Oxygen Cuvette
1978
Gas analytical processes for the determination of oxygen content or concentration are based partly on physical principles (e.g. mass spectrometry, gas chromatography, paramagnetic methods) and partly on chemical methods (e.g. gasometric, titrimetric, electrochemical or photometric methods).
ATTEMPTS TO PRODUCE SUPERHEAVY ELEMENTS IN REACTIONS BETWEEN HEAVY NUCLEI
1978
On the productivity and ecology of zooplankton and its role as food for fish in some lakes in Central Finland
1978
The study deals with the influence of some physical, chemical, and biotic factors upon the species composition, biomass, and production of zooplankton in several Finnish lakes. Different groups of zooplankton species are separated according to their relation to eutrophication and pollution caused by sewage and wastes from pulp and paper mills. The zooplankton biomass, estimated with the mean volumes of different species and stages, is considered in relation to eutrophication and pollution, and also to the production of phytoplankton. Some comparisons are made between different methods of estimating production. The significance of vendace (Coregonus albula L.) and smelt (Osmerus eperlanus L.…
Zur Entstehungsgeschichte der Pädagogik als Wissenschaft in der Neuzeit
1978
A contribution to the kinetics of the polymerization of styrene with CF3SO3H as catalyst
1978
The time dependence of the cationic polymerization of styrene in CH2Cl2 with CF3SO3H as catalyst can be formally described as being first-order with respect to monomer concentration [M]0. The reaction rate shows a third-order dependence in catalyst concentration [C]0. A high polymer and a low polymer polystyrene fraction are found at [M]0>0.2 mole · l−. The reaction rate of the high polymer fraction is proportional to [C] 0 3 , that of the low polymer fraction probably proportional to [C] 0 2 . The polymerization active species may thus be triple ions in the first and ion pairs in the second case.
On-line laser spectroscopy of short-lived mercury isotopes
1978
Evaluation of urodynamic studies by computer
1978
In an attempt to simplify urodynamic evaluation, the data obtained from cystometry, urethral profile and flowmetry were analysed using the ICS recommendations for standardization and terminology. All studies were compiled from check lists feasible for computation. The aim was to establish standards and "typical" changes for the normal bladder and pathological states to enable automatic readout of computed data. The results did, in fact, show "typical" changes but failed to establish standard measurements suitable for completely computed diagnoses.