Showing papers by "Technical University of Berlin published in 1970"
TL;DR: The ATP-synthesis and the electric phenomena on the thylakoid membrane have been studied under excitation of photosynthesis with short flash groups and it is shown that upon excitation with shortflash groups a certain electric potential difference is required before ATP can be synthesized.
Abstract: The ATP-synthesis and the electric phenomena on the thylakoid membrane have been studied under excitation of photosynthesis with short flash groups. The light induced electric potential difference has been measured by means of field indicating absorption changes around 523 nm.
It is shown that upon excitation with short flash groups a certain electric potential difference is required before ATP can be synthesized. Moreover it is confirmed that the ATP-synthesis is accompanied by an additional flux of protons down their electrochemical potential gradient. Correlation between the number of protons which have flowed across the ATPase coupled pathway, and the number of ATP-molecules which have been formed, yields a ratio H+/ATP = 3.
Since this ratio includes only those protons, which have interacted with the ATPase complex, it represents the lower limit for H+/ATP-ratios determined by any other method.
The necessity of a certain electric potential difference and the fact that 3 H+ have to be translocated down their electrochemical potential difference before one molecule of ATP can be synthesized is consistent with the chemiosmotic postulate, that the ADP ∼ P bond energy is derived from the electrochemical potential difference of the proton across the coupling membrane.
With respect to the alternative hypothesis for phosphorylation, the results impose grave restriction on a phosphorylation driven only by the free energy of a chemical intermediate, if this does exist at all.
147 citations
TL;DR: The perchlorate 6a reacts with phenyl isothiocyanate to give the betaine 19, and the reaction of 6a with mercury salts results in the formation of the mercury salt carbene complexes 12, 13 and 14 as discussed by the authors.
Abstract: Es werden einige 1.3-Diphenyl-imidazoliumsalze (6a–d) dargestellt und der Einflus des Anions auf die Protonenbeweglichkeit diskutiert. Das Perchlorat 6a wird mit Phenylsenfol (Kalium-tert.-butylat) zu dem Betain 19, mit Quecksilbersalzen zu den Quecksilbersalz-Carben-Komplexen 12, 13 und 14 umgesetzt. Die Bildungsmechanismen von 12–14 werden diskutiert.
Chemistry of Nucleophilic Carbenes, XX. HX-Elimination from 1,3-Diphenylimidazolium Salts. Mercury Salt Carbene Complexes
Some 1,3-diphenylimidazolium salts (6a–d) are synthesized, and the influence of the anion on the mobility of the proton is discussed. The perchlorate 6a reacts with phenyl isothiocyanate to give the betaine 19, and the reaction of 6a with mercury salts results in the formation of the mercury salt carbene complexes 12, 13 and 14. The mechanisms of formation of 12–14 are discussed.
124 citations
TL;DR: It will be demonstrated that, at first sight, the critical electric potential difference can be interpreted from the equilibrium thermodynamic formulation of the chemiosmotic hypothesis, but an inspection of the basic assumption for this interpretation, the reversibility of the ATPase system, reveals inconsistency with the apparent irreversibbility of the enzyme system.
Abstract: The physical meaning of the observed critical electric potential difference necessary for photophosphorylation is discussed. An interpretation of this phenomenon on the basis of the equilibrium thermodynamic formulation of the chemiosmotic hypothesis requires a reversible ATPase system. Contrary to this, ATP hydrolysis experiments seem to confirm that the Mg++dependent ATPase system of class 11-chloroplasts is irreversible in the absence of SH-compounds. This sheds doubt on the equilibrium thermodynamic interpretation of the critical electric potential difference for phosphorylation. However it can be shown, that the seeming irreversibility may be due to some trigger requirements of an intrinsically reversible ATPase system. This leads to an identification of the critical electric potential difference with the triggering level of the enzyme system. Two operational models for an ATPase system, whose activity is modulated by the electric potential difference, are derived. These account quantitatively for a set of experiments on the critical electric potential difference. In the preceding paper it has been shown that a certain electric potential difference across the thylakoid membrane is a necessary condition for photophosphorylation in short flash groups. Moreover it has been demonstrated that three protons have to be translocated across their electrochemical potential difference for any molecule of ATP which is synthesized [I]. Both results favour strongly the chemiosmotic hypothesis of Mitchell [2], who has postulated that an electric potential difference provides part of the free energy for the formation of ADP N P bonds. However, the mechanism which gives rise to a critical level of the electric potential difference has still to be interpreted. An attempt has been made to see whether this phenomenon can be understood from the same role of the electric potential difference, as an energy source for phosphorylation. It will be demonstrated that, at first sight, the critical electric potential difference can be interpreted from the equilibrium thermodynamic formulation of the chemiosmotic hypothesis. However, an inspection of the basic assumption for this interpretation, the reversibility of the ATPase system, reveals inconsistency with the apparent irreversibbility of the enzyme system. The latter has been concluded from hydrolysis experiments on class 11chloroplasts. This apparent irreversibility deserves a
123 citations
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123 citations
118 citations
TL;DR: In this paper, the authors discuss the biogenetical relationships between the tetrahedron of Helianthella uniflora and the acetophenone derivatives of the genus.
Abstract: Die zum Tribus Heliantheae gehorende Helianthella uniflora enthalt neben Spuren des weitverbreiteten Pentain-ens1 zahlreiche Acetophenon-Derivate(2–12), die alle einen Isopentenyl-Rest als Seitenkette oder als Teil von Ringsystemen besitzen. Die Strukturen ergeben sich aus den spektralen Daten. Ihre biogenetischen Beziehungen werden diskutiert.
New Isopentenyl-acetophenone Derivatives from Helianthella uniflora
Helianthella uniflora belonging to the tribe Heliantheae contains besides traces of the widespread pentayne-ene 1 several acetophenone derivatives all bearing an isopentenyl residue as sidechain or as part of ring systems. The structures are elucidated by their spectral data and the biogenetical relationships are discussed.
101 citations
TL;DR: In this article, the conditions given in the first section below, which are suf%cient for existence of periodic solutions, are known to be important for a different type of boundary value problem.
63 citations
01 Jul 1970
TL;DR: In this article, the problem of relating interaction coefficients applicable to conditions of constant chemical potential of one of the solute elements in a solution to the usual interaction coefficients at infinite dilution is treated.
Abstract: The problem of relating interaction coefficients applicable to conditions of constant chemical potential of one of the solute elements in a solution to the usual interaction coefficients at infinite dilution is treated. The formal relationships are applied to data on the Fe-Cr-C(sat) system at 1600°C and to results presented earlier on the Fe-P-C(sat) system at 1600°C. An alternative treatment for obtaining interaction coefficients for relatively concentrated solutions by a statistical technique is also presented and applied to data on the Fe-Cr-P system. When applicable, the former is considered to be more reliable.
60 citations
TL;DR: This chapter presents the X-ray structure research on the photosynthetic membrane and discusses the two-dimensional protein lattice of the chloroplast lamellae, and an evaluation appropriate to small angle scattering is performed using Gauss terms.
Abstract: Publisher Summary This chapter presents the X-ray structure research on the photosynthetic membrane. The photosynthetic splitting of water, the formation of adenosinetriphosphate and the reduction of nicotinamide–adenine–dinucleotidephosphate are accomplished within the green-plant cell in definite gross structures, the so-called “chloroplast lamellae.” From the X-ray research the photosynthetic lamellar system represents two types of lattice arrangements: a one-dimensional lattice formed by the internal layer structure of the lamellae and the stacking of the lamellae, and a two-dimensional lattice within the lamella plane. An example is included of this evaluation method for the case of the X-ray scattering of dry chloroplasts. The way the convolution square of the electron density distribution of the lattice cell can be found from the Q-function is presented, and the electron-density distribution is expressed as a summation of Gauss terms. The inner structure of the single membrane layer is examined. It discusses the two-dimensional protein lattice of the chloroplast lamellae. An evaluation appropriate to small angle scattering is performed using Gauss terms. The chapter also discusses the arrangement and distribution of the porphyrin rings of the chlorophylls.
45 citations
TL;DR: In this paper, it was shown that small optically active molecules which do not form a mesophase transform nematic into cholesteric mesophases, which is in excellent agreement with the optical properties of liquid cyrstals.
44 citations
TL;DR: In this paper, it is suggested that due to the adsorption of oxalate anions by the hydroxide, via solution formation of goethite is inhibited whereas the direct hematitization of the amorphous hydroxides particles is not.
TL;DR: In this article, the decay curves of some organic scintillator and dye molecules have been measured at different excitation intensities delivered by a mode-locked frequency-doubled ruby laser.
TL;DR: In this paper, non-catalytic Aldol additive reactions with Hydrate-forming Keto-Carbonyl Compounds are discussed, where the products are aducts of the aldol type.
Abstract: Hydratbildende cyclische 1. 2. 3-Tricarbonylverbindungen, z. B. 5–8, addieren enolisierbare Methylenverbindungen bei Raumtemperatur ohne Katalysator. Es entstehen aldolartige Addukte vom Typ A. Die Grenzen und der Mechanismus dieser Addition werden diskutiert ( vgl. Schema 4 ). – 2-Dicyanmethylen-indandion-(1.3) (40) reagiert mit Diaryldiazomethanen unter Bildung von Spiro-cyclopropan-Derivaten (vgl. 43 u. 44).
Non-catalytic Aldol Additions with Hydrate-forming Keto-Carbonyl Compounds
vic Cyclic 1, 2, 3-tricarbonyl compounds, e. g. 5–8, which form stable hydrates add to methylene compounds capable of enolisation. The products are aducts of the aldol type (A). The reaction proceeds at room temperature without the use of a catalyst. Scope and mechanism of these addition reactions are discussed. – 2-(Dicyanomethylen)indan- 1.3-dione (40) forms spiro cyclopropane derivatives (43, 44), when allowed to act on diaryldiazomethanes.
TL;DR: In this article, the fine structure of energy levels responsible for infrared luminescence of Cu2+-ions in II-VI-compounds, and corresponding g-values are calculated on the basis of the most general effective Hamiltonian.
TL;DR: In this article, the authors investigated the following parameters: the emission spectrum, the excitation spectra for the two emission bands, and the temperature dependences of these, and proposed to explain the 2.0 μm-IR emission to the 5 E → 5 T 2 transition.
TL;DR: In this paper, the oscillator strengths of the low-lying resonance lines of rare gas atoms have been measured by means of high-resolution electron spectroscopy using 36 keV electrons.
TL;DR: In this paper, die Stereochemie der Claisen-Umlagerung wird diskutiert, in der beiden 24-epimeren Sterine 1.
Abstract: Das Athinylcarbinol 3 aus 3β-Acetoxy-22.23-dinor-5α-cholen-(7)-aldehyd (2) und Butin-(1)-ylmagnesiumbromid wird zum Allylalkohol 4 hydriert, der bei der Claisen-Umlagerung mit dem keten-O.N-acetal5 das Amid 7 ergibt. Lithiumalanatreduktion und CopeAbbau fuhren zum Titelsterin 1. Aus den epimeren Formen von 4 erhalt man in stereospezifischer Reaktion die beiden 24-epimeren Sterine 1. Die Stereochemie der Claisen-Umlagerung wird diskutiert.
TL;DR: It is shown that cells of the strain 211 of Saccharomyces cerevisiae incorporate exogenous 2-14C-TMP specifically into DNA.
TL;DR: In Eclipta erecta L. T. as mentioned in this paper, 16 new biogenetically closely related thiophene derivatives are found, although only very small amounts of material were isolated, and often the fractions were not completely pure.
Abstract: In Eclipta erecta L. werden neben bereits bekannten Verbindungen 16 neue biogenetisch eng verwandte Thiophen-Derivate nachgewiesen. Aufgrund der spektroskopischen Daten der z. T. nur in sehr geringer Menge und haufig nicht rein isolierten Chromatogrammfraktionen konnen die Strukturen 7, 9 und 13–26 vorgeschlagen werden.
Polyacetylene Compounds, 173. Substances from Eclipta erecta L.
Besides already known compounds in Eclipta erecta L. 16 new biogenetically closely related thiophene derivatives are found. Although in some cases only very small amounts of material were isolated, and often the fractions were not completely pure, the structures 7, 9, and 13–26 are proposed from spectral data.
TL;DR: In this article, the trapped magnetic flux was investigated in superconducting microcylinders (inner diameter < 1 μm) and was found to be quantized in integer multipleshc/2e.
Abstract: By use of electron interferometry the trapped magnetic flux was investigated in superconducting microcylinders (inner diameter < 1 μm). Even in thin walled cylinders (wall thickness < penetration depth) at temperatures near the superconducting transition the flux was found to be quantized in integer multipleshc/2e.
TL;DR: The first version of the autobiography of John Wallis (1616-1703) was published in the early 17th century as discussed by the authors, but it is incomplete and to the best of our knowledge, still unpublished.
Abstract: In old age John Wallis (1616-1703) wrote an autobiography in response to the repeated requests of his friend Thomas Smith (1638-1710). Apart from the purely biographical interest, it is a valuable historical source for the origins of the Royal Society and for the Assembly of Divines at Westminster in the 1640s. Besides the final version, excerpts of which have often been quoted, there still exists Wallis’s first draft of this autobiography—though unfortunately incomplete and, to the best of my knowledge, hitherto unpublished. Both texts, transcribed from the manuscripts, are printed in this article side by side. This shows how Wallis greatly altered and extended his first draft before he had a copy made for Smith. The notes subjoined to this article contain additional information about persons and places mentioned by Wallis.
TL;DR: The history of mesoionic compounds can be found in this paper, where a short introduction deals with the history of the mesoionic compounds and their relationships with other compounds, e.g., 2.3-dithioxopropane.
Abstract: Bei der Einwirkung von 4 Mol Kalium-athylxanthogenat (5) auf 1 Mol 1.1.3.3-Tetrabrom-1.3-diphenyl-aceton (4) in polaren Losungsmitteln, z. B. DMF,-entsteht der mesoionische Aromat 8. Dieser ist valenzisomer mit dem 2-Oxo-1.3-dithioxo-propan 7, das als mogliche Zwischenstufe bei der Bildung von 8 angenommen wird. Die negative Solvatochromie, hypsochromer Effekt, wird besprochen. Die IR-Spektren von 8 und seines gelben Perchlorats 11 werden verglichen. Mit Hydrazinhydrat liefert 8 ebenso wie das Triketonhydrat 12 das Pyrazolderivat 15. Die Behandlung von 8 mit Raney-Nickel fuhrt zu einem Produkt, das nach der Einwirkung von aktiviertem Mangan(IV)-oxid Dibenzylketon liefert. Natriumboranat reduziert 8 zu einer Verbindung, die mit aktiviertem Mangen(IV)-oxid 8 zuruckbildet. Bei der Thermolyse (275°) von 8 werden als Hauptprodukte elementarer Schwefel und Tetraphenyl-p-benzochinon (17) gewonnen. Es wird diskutiert, ob 17 via 7 entsteht.
Einleitend wird auf die Geschichte der mesoionischen Verbindungen eingegangen.
Mesoionic Aromatic Compounds, II. Mesoionic 3.5-Diphenyl-1.2-dithiolylium-4-olate, a Valence Isomer of 2-Oxo-1.3-dithioxo-1.3-diphenylpropane
The mesoionic aromatic compound 8 is obtained by allowing potassium ethylxanthate (5) (4 moles) to react with 1.1.3.3-tetrabromo-1.3-diphenylacetone (4) (1 mole) dissolved in a polar solvent, e. g. dimethylformamide. 8 is a valence isomer of the 2-oxo-1.3-dithioxopropane 7, which may be an intermediate in the formation of 8. The negative solvatochromy, the hypsochromic effect, shown by 8 is discussed. The i.r. spectra of 8 and its yellow perchlorate 11 are compared with each other. 8 as well as the triketone hydrate 12 react with hydrazine to give the pyrazole derivative 15. When Raney-nickel is allowed to react with 8 a product is obtained which after treatment with activated manganous dioxide (MnO2) yields dibenzylketone. Sodium boranate reacts with 8 to give a product which is reconverted to 8 upon treatment with activated manganous dioxide. Pyrolysis (275°) of 8 furnishes as main products sulfur and 2.3.5.6-tetraphenylbenzoquinone (17), the formation of 17 via 7 is discussed. – A short introduction deals with the history of mesoionic compounds.
TL;DR: In this paper, single crystals of the system CdCr2(S1−xSex)4 have been prepared by chemical transport with I2/AlCl3 mixtures and by flux growth from solutions in molten CdCl2.
Abstract: Im System CdCr2(S1−xSex)4 wurden Einkristalle durch Transportreaktion mit J2/AlCl3-Gemischen als Transportmittel und durch Kristallisation aus CdCl2-Schmelzlosungen hergestellt.
Single crystals of the system CdCr2(S1−xSex)4 have been prepared by chemical transport with I2/AlCl3 mixtures and by flux growth from solutions in molten CdCl2.
TL;DR: In Fischer-type reactions enhydrazines 3a and 3b, prepared from cyclohexane-1,3-dione and dimedone respectively, respectively, react with cycloenanone to form octahydrocarbazolones 5a and 5b and with 3-keto steroids to form tetrahydroindolone steroids 9a, 9b and 10 as mentioned in this paper.
Abstract: Aus einigen β-Diketonen und β-Ketoestern werden stabile Enhydrazine dargestellt. Die aus Cyclohexandion-(1.3) und Dimedon gewonnenen Enhydrazine 3a und 3b werden in Fischer-analogen Reaktionen mit Cyclohexanon zu den Octahydrocarbazolonen 5a und 5b und mit 3-Keto-steroiden zu den Tetrahydroindolon-steroiden 9a, 9b und 10 umgesetzt.
10 umgesetzt.
Stable enhydrazines are prepared from a number of β-diketones and β-keto esters. In Fischer-type reactions enhydrazines 3a and 3b, prepared from cyclohexane-1,3-dione and dimedone, respectively, react with cyclohexanone to form octahydrocarbazolones 5a and 5b and with 3-keto steroids to form tetrahydroindolone steroids 9a, 9b and 10.
TL;DR: In this paper, the anomalous self-diffusion behavior of the elemental semiconductors and correlation considerations were discussed and the presented results for selenium were shown to be in agreement.
Abstract: Self-diffusion measurements have been carried out in single crystals of the semiconductor element selenium using a residual activity method and Se-75 as the tracer in the temperature range 152 to 215 °C. In the direction of the trigonal axis (| c-axis) the data of the lattice diffusion can be represented by D⟂ = 0.2 exp (—1.2 eV/kT) cm2 s−1. The diffusion along the short circuit paths can be approximately described by the values Q≈ 0.5 eV and Q≈ 0.7 eV for the activation energy and by diffusion coefficients between 5 × 10−10 and 10−8 cm2 s−1 in the temperature range considered. The vacancy formation enthalpy in selenium is estimated to be about 0.75 eV. From the diffusion data determined the vacancy migration enthalpy is estimated to be about 0.5 eV along the c-axis and 0.7 eV perpendicular to the c-axis. It is possible to explain the self-diffusion in selenium on the basis of a vacancy mechanism. The anomalous self-diffusion behaviour of the elemental semiconductors and correlation considerations are discussed. Several typical features were found and the presented results for selenium are shown to be in agreement.
Die Selbstdiffusion in Einkristallen des Halbleiterelements Selen wurde im Temperaturbereich 152 bis 215 °C mit Hilfe des Leitisotops Se-75 und der Restaktivitatsmethode gemessen. Die Resultate der Gitterdiffusion in Richtung der trigonalen Achse (| c) lassen sich durch D⟂ = 0,2 exp (— 1,2 eV/kT) cm2 s−1 beschreiben, wahrend far die Richtung senkrecht zur trigonalen Achse (⟂ c) D≈ = 102 exp (— 1,4 eV/kT)cm2 s−1 gilt. Die Diffusion entlang der Kurzschluswege kann im untersuchten Temperaturbereich naherungsweise durch die Aktivierungsenergien Q| ≈ 0,5 eV bzw. Q⟂ ≈ 0,7 eV und Diffusionskoeffizienten zwischen 5 × 10−10 und 10−8 cm2 s−1 charakterisiert werden. Die Bildungsenthalpie fur Leerstellen in Selen wurde zu etwa 0,75 eV abgeschatzt. Aus einer Analyse der Diffusionsdaten wurde fur die Leerstellenwanderungsenthalpie in Richtung der c-Achse der Wert 0,5 eV und senkrecht dazu 0,7 eV abgeschatzt. Es kann angenommen werden, das die Selbstdiffusion in Selen durch einen Leerstellenmechanismus erfolgt. Die Besonderheiten des Selbstdiffusionsverhaltens der Elementhalbleiter und Korrelationen werden in der Diskussion behandelt. Es wurden verschiedene gemeinsame Tendenzen gefunden, die auch von Se befolgt werden.
TL;DR: In this article, the formation of methylene bisxanthogenates by action of diaryldiazomethanes on dialkyl xanthogen disulfides and their fragmentation is discussed.
Abstract: Die unter S—S-Insertion verlaufenden Reaktionen der Diaryldiazomethane 1 mit den Dixanthogenen 2 fuhren gemas (2) zu den Diarylmethylen-bis-xanthogenaten 3, deren Konstitution durch direkten Vergleich mit den aus den gem. Dichloriden 4 und den Kaliumxanthogenaten 5 nach (3) gewonnenen Verbindungen sowie durch die NMR-Spektren sichergestellt wurde. Dibenzyl- und Dibenzoyldisulfid sowie Tetramethyl-thiuramdisulfid lassen sich mit Diphenyldiazometan nicht analog umsetzen. Die Bis-xanthogenate 3 fragmentieren bei Raumtemp. in Festsubstanz mit Ausnahme der Diphenyl-Derivate 3a und 3e, in Losungsmitteln jedoch ohne Ausnahme, in die entsprechenden Thioketone, siehe Gleichungen (4)–(6). Warmezufuhr und Losungsmittel wie Athanol, DMF oder Pyridin begunstigen die Fragmentierung, deren Mechanismus diskutiert wird.
Organic Sulfur Compounds, LX. The Formation of Methylene Bisxanthogenates by Action of Diaryldiazomethanes on Dialkyl Xanthogen Disulfides and their Fragmentation
S—S-Insertion reactions were observed when diaryldiazomethanes 1 were allowed to react with dialkyl xanthogen disulfides 2 (see (2)). Identification of the reaction products asmethylene bisxanthogenates 3 was confirmed by additional preparation of 3 by reaction of the gem. dichlorides 4 with potassium xanthogenates 5 (see (3)) as well as by the n.m.r. spectra. Dibenzyl-, dibenzoyl-disulfides, and tetramethyl-thiuramdisulfide do not undergo an analogous reaction with diphenyldiazomethane. The bisxanthogenates 3 decompose at room temprature in the solid state and in solution to give the corresponding thioketones (see (4)–(6)). The diarylderivatives 3a and 3e, however, are stable in the solid state. The fragmentation is facilitated by using ethanol, dimethylformamide or pyridine as solvents. The mechanism of the fragmentation is discussed.
TL;DR: In weiteren Grindelia-Arten werden einige neue C10-Acetylenverbindungen (1-3, 8, 9, 13, 14, 22, 23) nachgewiesen, die die biogenetische Beziehung in dieser Gattung aufzeigen as discussed by the authors.
Abstract: In weiteren Grindelia-Arten werden einige neue C10-Acetylenverbindungen (1-3, 8, 9, 13, 14, 22, 23) nachgewiesen, die die biogenetische Beziehung in dieser Gattung aufzeigen. Futterungsversuche zeigen weitere Einzelheiten uber die Biogenese der C10-Verbindungen.
Polyacetylenic Compounds, 178. Constituents of Grindelia Species
The investigation of further Grindelia species shows the presence of some new C10-acetylenic compounds (1-3, 8, 9, 13, 14, 22, 23) representing biogenetical relationships in this genus. Feeding experiments furnish more details of the biogenesis of the C10-compounds.