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  • 1
    Electronic Resource
    Electronic Resource
    Compartmental distribution and redistribution of abscisic acid in intact leaves (1992)
    Springer
    Planta 187 (1992), S. 14-25 
    Details
    ISSN: 1432-2048
    Keywords: Abscisic acid (compartmentation in leaves) ; Computer model (ABA compartmentation) ; Drought stress (quantification) ; Leaf (ABA compartmentation) ; pH shift ; Stomatal regulation Valerianella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using experimental information obtained in earlier studies on the permeabilities of mesophyll and guard-cell membranes to abscisic acid (ABA), and on stress-induced pH shifts in the apoplasm and in symplasmic compartments (Hartung et al., 1988, Plant Physiol. 86, 908–913; Hartung et al. 1990, BPGRG Monogr. 215–235), a mathematical model is presented which will permit computer analysis of the stress-induced redistribution of ABA amongst different leaf cell types (mesophyll, epidermis, guard cells, phloem cells) and their compartments (cell wall, cytosol, chloroplast stroma, vacuole). Metabolism and conjugation of ABA and its transport in the xylem and the phloem are also taken into consideration. We ask whether the stressinduced redistribution of ABA is fast and intensive enough to induce stomatal closure within a few minutes. The model can be adapted to any other weak acid or base, e.g. to other phytohormones (auxins, gibberellins), which differ from ABA, e.g. by their membrane conductances, anion permeabilities and pKa values. Our wholeleaf model can predict the time course and the compartmentation of, for example, phytohormone concentrations as a function of changing source-sink patterns (e.g. by compartmental pH shifts in the leaf lamina). An analysis of the present knowledge of the ABA physiology of leaves and studies on stress effects are presented in subsequent publications. In this communication we describe the whole-leaf model and present and discuss all necessary morphological (volumes, surfaces etc.) and physiological (pH, membrane conductances etc.) parameters of an unstressed leaf of Valerianella locusta L. We draw fundamental conclusions by comparing determined and calculated ABA concentrations in the leaf-cell compartments. We found that the model predictions are close to measured data, and we conclude that in unstressed leaves ABA is close to flux equilibrium amongst the different tissues and compartments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201619
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  • 2
    Electronic Resource
    Electronic Resource
    Compartmental distribution and redistribution of abscisic acid in intact leaves (1992)
    Springer
    Planta 187 (1992), S. 37-47 
    Details
    ISSN: 1432-2048
    Keywords: Abscisic acid (compartmentation in leaves) ; Computer model (ABA compartmentation) ; Drought stress (quantification) ; Leaf (ABA compartmentation) ; pH-shift ; Stomatal regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using a computer model written for whole leaves (Slovik et al. 1992, Planta 187, 14–25) we present in this paper calculations of abscisic acid (ABA) redistribution among different leaf tissues and their compartments in relation to stomatal regulation under drought stress. The model calculations are based on experimental data and biophysical laws. They yield the following results and postulates: (i) Under stress, compartmental pH-shifts come about as a consequence of the inhibition of the pH component of proton-motive forces at the plasmalemma. There is a decrease of net proton fluxes by about 8.6 nmol · s−1 · m−2. (ii) Using stress-induced pH-shifts we demonstrate how ‘stress intensities’ can be quantified on a molecular basis. (iii) As the weak acid ABA is the only phytohormone which behaves in vivo and in vitro ideally according to the Henderson-Hasselbalch equation, pH-shifts induce a complicated redistribution amongst compartments in the model leaf. (iv) The final accumulation of ABA in guard-cell walls is intensive: up to 16.1-fold compared with only up to 3.4-fold in the guard-cell cytosol. We propose that the binding site of the guard-cell ABA receptor faces the apoplasm. (v) A twoto three-fold ABA accumulation in guard-cell walls is sufficient to induce closure of stomata. (vi) The minimum time lag until stomata start to close is 1–5 min; it depends on the stress intensity and on the guard-cell sensitivity to ABA: the more moderate the stress is, the later stomata start to close or they do not close at all. (vii) In the short term, there is almost no influence of the velocity of pH-shifts on the velocity of the ABA redistribution, (viii) Six hours after the termination of stress there is still an ABA concentration 1.4-fold the initial level in the guard-cell cytosol (delay of ABA relaxation, ‘aftereffect’), (ix) The observed ‘induction’ of net ABA synthesis after onset of stress may be explained by a decrease in cytosolic ABA degradation. About 1 h after onset of stress the model leaf would start to synthesise ABA (and its conjugates) automatically, (x) This ABA net synthesis serves to ‘inform roots’ via an increased ABA concentration in the phloem sap. The stress-induced ABA redistribution is per se not sufficient to feed the ploem sap with ABA. (xi) The primary target membrane of ‘stress’ is the plasmalemma, not thylakoids. (xii) The effective ‘stress sensor’, which induces the proposed signal chain finally leading to stomatal closure, is located in epidermal cells. Mesophyll cells are not capable of creating a significant ABA signal to guard cells if the epidermal plasmalemma conductance to undissociated molecular species of ABA (HABA) is indeed higher than the plasmalemma conductance of the mesophyll (plasmodesmata open), (xiii) All model conclusions which can be compared with independent experimental data quantitatively fit to them. We conclude that the basic experimental data of the model are consistent. A stress-induced ABA redistribution in the leaf lamina elicits stomatal closure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201621
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  • 3
    Electronic Resource
    Electronic Resource
    A New Route to Alkoxy Radicals  -  Photochemical Reactions with (Alkylperoxy)cobaloximes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 387-390 
    Details
    ISSN: 0009-2940
    Keywords: Peroxy compounds ; Cobaloximes ; Oxygen insertion ; Radicals, alkoxy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkoxy radicals have been generated by photochemical reactions of (alkylperoxy)cobaloximes 1. The occurrence of alkoxy radicals has been proved by characteristic cyclization and β-scission reactions of the reactive intermediates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240223
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  • 4
    Electronic Resource
    Electronic Resource
    Polar Effects in Halogen Abstraction Reactions of Alkyl Radicals (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1777-1779 
    Details
    ISSN: 0009-2940
    Keywords: Polar effects ; Radical clock ; Cobaloximes, alkyl ; Radicals, alkyl ; Chlorine abstraction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a series of structurally similar alkyl radicals 1a-c the tertiary 1,1-dimethyl-5-hexenyl radical 1c reacts 30 times faster with carbon tetrachloride than the primary 5-hexenyl radical 1a. The reactivity of the secondary 1-methyl-5-hexenyl radical 1b aligns itself in between the primary and the tertiary radical 1a and 1c. The results indicate that the increasing nucleophilicity of the alkyl radicals is the major factor contributing to the reactivity.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250734
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  • 5
    Electronic Resource
    Electronic Resource
    What is Different in Photochemical Reactions of Primary and Secondary Alkylcobaloximes with and without Radical Traps? (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1187-1191 
    Details
    ISSN: 0009-2940
    Keywords: Cobaloximes, alkyl- ; 5-Hexenyl, cyclization to cyclopentylmethyl ; Radicals, alkyl ; Abstraction of bromine and chlorine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical cyclization and halogen abstraction reactions of secondary alkylcobaloximes 1b and 1d compared to their primary counterparts 1a and 1c show an enhanced reactivity of secondary alkylcobaloximes: Thus, cyclohexylcobaloxime 1d reacts 13 times faster with CCl4 than n1-hexylcobaloxime 1c, 6-hepten-2-yl-cobaloxime 1b rearranges 58 times faster to its cyclopentylmethyl isomer 4b than 5-hexenylcobaloxime 1a. Although free alkyl radicals are reactive intermediates in photolytic conversions of alkylcobaloximes 1 in organic solvents, the presence of BrCCl3 or bromobenzene in photoreactions of primary alkylcobaloximes 1a and 1c seems to cause a more efficient homolytic cleavage of the Co - C bond.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260519
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  • 6
    Electronic Resource
    Electronic Resource
    Preparation and Properties of Alkylbis(dimethylglyoximato)rhodium(III) ComplexesDedicated to Professor Dr. Klaus Hafner on the occasion of his 65th birthday. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1193-1200 
    Details
    ISSN: 0009-2940
    Keywords: Alkylrhodoximes ; Radicals, alkyl ; Halogen abstraction ; Carbon-carbon bond formation ; Stereochemistry ; Photoreactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Primary, secondary, and tertiary alkylrhodoximes 1 were prepared from alkyl bromides and tosylates 4 and the trans1-dichlororhodium complex 3. X-ray crystallography of the previously unknown tert1-butylrhodoxime 1k reveals structural features of this tert-s̰1-alkylrhodium compound. Photochemical homolytic cleavage of the Rh - C bond in alkylrhodoximes 1 only occurs in the presence of efficient radical traps which allow further mechanistic studies.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260520
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  • 7
    Electronic Resource
    Electronic Resource
    Werkstoff-Datenbank (1993)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 44 (1993), S. 410-415 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Material databaseThis paper describes a new materials database named SWDB. SWDB is the German abbreviation for „Sollwert-Werkstoff-Datenbank“ and should be read as „Specified-Materials-Database“. SWDB is a state of the art user friendly materials database which provides adequate information on standardized and not standardized materials characteristics of solid materials from ferrous and non-ferrous metals and other metallic alloys currently used in engineering practice. Apart from the chemical composition and mechanical-technological properties of metallic materials based on various standards and specifications, the database includes reference to a large number of possible alternative materials in a concise and pregnant form which is transparent and easily accessible for application engineers. The material data are composed on the basis of an absolutely new structured model and are shown as a function of the specified material, product shape, dimension, delivery condition and sampling.SWDB includes additional information on physical properties as well as exhaustive information on heat treatment, hot and cold forming, weldability and hints for application. The SWDB has a dual character: on the one hand it can be operated as an individual and independent database, on the other hand as a satellite database to support the corrosion database within the information system on corrosion and protection, „CORIS“.
    Notes: Die neu entwickelte Sollwert-Werkstoff-Datenbank (SWDB) ist eine benutzerfreundliche Werkstoff-Datenbank, die Informationen über genormte und nicht genormte Werkstoff-Kennwerte massiver, metallischer Werkstoffe bereitstellt. Der Inhalt dieser Datenbank setzt sich zusammen aus Solldaten von ingenieurmäßig gebräuchlichen, massiven Werkstoffen aus Eisen- und Nichteisenmetallen. Neben der chemischen Zusammensetzung und den mechanisch-technologischen Eigenschaften von metallischen Werkstoffen nach verschiedenen Normen und Spezifikationen sind eine Vielzahl möglicher alternativer Werkstoffkandidaten in kurzer, prägnanter und für den Anwender gut einsehbarer Form referiert. Die Daten sind auf der Basis eines völlig neu strukturierten Modells aufgebaut und in Abhängigkeit vom spezifizierten Werkstoff von der Erzeugnisform, der Abmessung, dem Lieferzustand und von der Probennahme wiedergegeben.Außerdem enthält die SWDB zusätzliche Informationen über physikalische Kennwerte sowie zahlreiche Angaben zur Wärmebehandlung, Warm- und Kaltformgebung, Schweißbarkeit und Anwendungshinweise. Die SWDB hat eine doppelte Funktion: einerseits arbeitet sie als unabhängige Datenbank eigenständig, andererseits als Satellit-Datenbank, die die Korrosionsfakten-Datenbank im Informationssystem für Korrosion und Korrosionsschutz „CORIS“ unterstützt.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19930441005
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  • 8
    Electronic Resource
    Electronic Resource
    Coronanden mit 1,2-Dithio-ethen-Einheiten. II. Kristallstrukturen der beiden Thiakronenether 8,9-Dicyan-8,9-didehydro-7,10-dithia[12]krone-4 und 11,12-Dicyan-11,12-didehydro-10,13-dithia[15]krone-5 (1992)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 334 (1992), S. 155-160 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coronands with 1,2-Dithio-ethene Units. II. Crystal Structures of the Two Crown Thioethers 8,9-Dicyano-8,9-didehydro-7,10-dithia-[12]crown-4 and 11,12-Dicyano-11,12-didehydro-10,13-dithia[15]crown-5The structures of the title compounds have been determined by X-ray analysis. Both thioethers crystallize in the monoclinic system with the following crystal data. Dithia-[12]crown-4: a = 751.7(1), b = 1010.4(1), c = 1639.8(2) pm, β = 95.08(1)°, Z = 4, space group P21/n; dithia[12]crown-5: a = 1169.9(3), b = 916.7(3), c = 1414.1(4)pm, β = 92.51(2)°, Z = 4, space group P21/c. The structures were refined to final R = 0.048 (Rw = 0.031) and 0.040 (0.046), respectively. They are characterized by their structural parameters (bond lengths and angles, torsion angles, l.s. planes) and discussed in special consideration of the ring conformation and the geometric arrangement of the donor atoms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19923340211
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  • 9
    Electronic Resource
    Electronic Resource
    Alkylthio-substituierte Bis(benzol-1,2-dithiolato)zinkate, Benzol-1,2-dithiole und -1,2-dithiolate - Edukte für Dibenzo[c,g](1,2,5,6)tetrathiocine und Benzo[c](1,2,3)-trithiole; Untersuchungen zu Benzodithieten und ortho-DithiobenzochinonenOrganische Elektronenleiter und Vorstufen. XVII [1] (1994)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 444-451 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Using benzenehexathiolate 1 it is possible to synthesize alkylthio-substituted benzo-1,3-dithiole-2-thiones 2, or -ones 3 and benzo-di(1,3-dithiole-2-thiones) 4, or -ones 5, resp., which were cleaved under basic conditions. The generated benzene-1,2-dithiolates 7 were isolated as benzene-dithiolato zincates 8, benzene-1,2-dithioles 11, and benzene-1-thiole-2-thiolates 10. Dibenzo[c,g](1,2,5,6)-tetrathiocins 9 were synthesized by oxidation of 7 or 8 in good yields. For the per(methylthio)-substituted tetrathiocin 9a the twist conformation was proved by x-ray structure analysis.The tetrathiocin 9a was probably formed via the orthodithiobenzoquinone 13a. Photolysis of 3a at room temperature in solution led to 9a and tetrakis(methylthio)benzo[c] (1,2,3)trithiole 12a as the main product, which was also formed by irradiation of 9a. The trithioles 12 were formed from 8 by reaction with sulfur dichloride. 12a was investigated by x-ray structure analysis. ortho-Dithiobenzoquinone 13c can be claimed as an intermediate upon irradiation of benzo-1,3-dithiol-2-one 3c in an argon matrix at 10 K. Depending on the wavelength the equilibrium lies either on the side of dithiobenzoquinone 13c or benzodithiete 14c. The same is true for system 15/16, which can be reached by flash vacuum pyrolysis of 3c.
    Notes: Alkylthiosubstituted Bis(benzene-1,2-dithiolato)zincates, Benzene-1,2-dithioles, and -1,2-dithiolates - Educts for Dibenzo[c,g](1,2,5,6)tetrathiocins, and Benzo[c](1,2,3)trithioles; Investigations on Benzodithietes and ortho-Dithiobenzochinones
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19943360512
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  • 10
    Electronic Resource
    Electronic Resource
    Synthese, koordinationschemische und massenspektrometrische Charakterisierung neuartiger carboxylsubstituierter N-(Thiocarbamoyl)-benzamidine (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 359-366 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Coordination Chemistry and Mass Spectrometric Fragmentation of New N-(Thiocarbamoyl)-benzamidinesSyntheses of N-(thiocarbamoyl)benzamidines from benzimidoylchlorides and aromatic amino acids as starting materials are reported. The prepared compounds were used as ligands for complexing nickel(II) and copper(II)ions. The benzamidines were characterized by mass spectrometric methods. The fragmentation pattern of the benzamidines was derived from the corresponding MIKE-spectra.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320313
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