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  • Articles: DFG German National Licenses  (23)
  • Chemistry  (20)
  • amino acids  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Influence of Etherel and Gibberellic Acid on Carbon Metabolism, Growth, and Essential Oil Accumulation in Spearmint (Mentha Spicata) (1999)
    Springer
    Photosynthetica 36 (1999), S. 509-517 
    Details
    ISSN: 1573-9058
    Keywords: amino acids ; chlorophyll ; 14CO2- and 14C-sucrose incorporation ; organic acids ; primary photosynthetic metabolites ; stem ; stomatal conductance ; sugars ; transpiration rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in growth parameters and 14CO2 and [U-14C]-sucrose incorporation into the primary metabolic pools and essential oil were investigated in leaves and stems of M. spicata treated with etherel and gibberellic acid (GA). Compared to the control, GA and etherel treatments induced significant phenotypic changes and a decrease in chlorophyll content, CO2 exchange rate, and stomatal conductance. Treatment with etherel led to increased total incorporation of 14CO2 into the leaves wheras total incorporation from 14C sucrose was decreased. When 14CO2 was fed, the incorporation into the ethanol soluble fraction, sugars, organic acids, and essential oil was significantly higher in etherel treated leaves than in the control. However, [U-14C]-sucrose feeding led to decreased label incorporation in the ethanol-soluble fraction, sugars, organic acids, and essential oils compared to the control. When 14CO2 was fed to GA treated leaves, label incorporation in ethanol-insoluble fraction, sugars, and oils was significantly higher than in the control. In contrast, when [U-14C]-sucrose was fed the incorporation in the ethanol soluble fraction, sugars, organic acids, and oil was significantly lower than in the control. Hence the hormone treatment induces a differential utilization of precursors for oil biosynthesis and accumulation and differences in partitioning of label between leaf and stem. Etherel and GA influence the partitioning of primary photosynthetic metabolites and thus modify plant growth and essential oil accumulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007083802765
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  • 2
    Electronic Resource
    Electronic Resource
    The Substrate Utilization and Concentration of 14C Photosynthates in Citronella under Fe Deficiency (1998)
    Springer
    Photosynthetica 35 (1998), S. 391-398 
    Details
    ISSN: 1573-9058
    Keywords: acetate ; amino acids ; 14CO2 ; Cymbopogon winterianus ; oil ; organic acids ; primary and secondary metabolites ; sugars ; [U-14C] ; [U-14C] saccharose incorporation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the utilization pattern of primary substrate, viz. [U-14C] acetate, 14CO2 and [U-14C] saccharose, and the contents of 14C fixation products in photosynthetic metabolites (sugars, amino acids, and organic acids) were determined in Fe-deficient citronella in relation to the essential oil accumulation. There was an overall decrease in photosynthetic efficiency of the Fe-deficient plants as evidenced by lower levels of incorporation into the sugar fraction and essential oil after 14CO2 had been supplied. When acetate and saccharose were fed to the Fe-deficient plants, despite a higher incorporation of label into sugars, amino acids, and organic acids, there was a lower incorporation of these metabolites into essential oils than in control plants. Thus, the availability of precursors and the translocation to a site of synthesis/accumulation, severely affected by Fe deficiency, is equally important for the essential oil biosynthesis in citronella.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006964302422
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of Zn deficiency on net photosynthetic rate, 14C partitioning, and oil accumulation in leaves of peppermint (1997)
    Springer
    Photosynthetica 33 (1997), S. 71-79 
    Details
    ISSN: 1573-9058
    Keywords: amino acids ; biomass ; chlorophyll ; 14CO2 and [U-14C] sucrose incorporation ; essential oils ; leaf development ; organic acids ; primary photosynthates ; sugars ; Zn-stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in growth, CO2 exchange rate, and distribution of photosynthetically fixed 14CO2 into the primary photosynthetic metabolic pool (sugars, amino acids and organic acids) and essential oil accumulation were determined in leaves (leaf positions 1-6 from apex) of developing peppermint grown in a solution culture at Zn concentrations of 0 and 0.05 g m-3. There was a significant decrease in 14C incorporation in total, ethanol-soluble and ethanol-insoluble fractions in Zn deficient plants at all leaf positions. 14C incorporated in essential oil and in sugars were significantly higher in leaf pairs 1 to 3 than in leaf pairs 4 to 6. 14C incorporation into amino acids and organic acids was higher in all leaf pairs in Zn deficient plants. Statistical analysis showed a positive significant association between Zn content of leaf and 14C incorporation into ethanol-soluble fraction and sugars and a negative correlation with 14C incorporation into amino acids and organic acids. Hence the content of sugars in leaves significantly influences essential oil accumulation under Zn stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022127305883
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  • 4
    Electronic Resource
    Electronic Resource
    Drag coefficient and velocity of rise of a single collasping two-phase bubble (1997)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 1955-1963 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The velocity of rise and the drag of a single vapor bubble collapsing in another immiscible liquid were measured experimentally. During the process of collapse, the dispersed-phase vapor bubble was transformed to a two-phase bubble with condensate accumulating at the rear of the two-phase bubble and vapor at its top. Such a configuration of a two-phse bubble is commonly known as a drobble. Experimental data for the six pairs of liquids covered a range of drobble (two-phase bubble) Reynolds numbers from 0.003 to 3,000. Two regimes of drobble movement were encountered. In the first regime (Re 〈 100), the drobble maintained its sphericity, and the observed drag was less than the solid-sphere drag predicted by the established solid sphere or Hadamard et al. fluid-sphere drag models. In the second regime, the drobble was deformed and oscillated; the observed drag departed suddenly from predictions of spherical models and increased with increasing Reynolds numbers. The critical Reynolds number covered a range from 100 to 1,000. Empirical models for drobble velocity and drag coefficient are derived.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690430805
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of fillers on the rheological behavior of thermoplastic 1,2 polybutadiene rubber (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 648-654 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The influence of fillers like clay, silica, and carbon black on the rheological properties of 1,2 polybutadiene has been studied using a capillary rheometer. Silica filled compound exhibited the highest viscosity and clay filled compound the lowest viscosity at all shear rates. The effect of filler loading and temperature on the Theological behavior has also been studied. Smooth extrudates were obtained in most of the cases and die swell was lower for silica and carbon black filled compounds than for clay filled compounds. Rheograms of different 1,2 polybutadiene systems have been found to merge into a master curve using modified viscosity and shear rate functions that contain melt flow index as a parameter.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760281003
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  • 6
    Electronic Resource
    Electronic Resource
    Studies of conformational isomerism in α-melanocyte stimulating hormone by design of cyclic analogues (1998)
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 155-167 
    Details
    ISSN: 0006-3525
    Keywords: α-MSH ; [D-Phe7]α-MSH ; isomerism ; cyclic analogues ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Results of energy calculations for α-MSH (α-melanocyte stimulating hormone, Ac-Ser1-Tyr2-Ser3-Met4-Glu5-His6-Phe7-Arg8-Trp9-Gly10-Lys11-Pro12-Val13-NH2) and [D-Phe7]α-MSH were used for design of cyclic peptides with the general aim to stabilize different conformational isomers of the parent compound. The minimal structural modifications of the conformationally flexible Gly10 residue, as substitutions for L-Ala, D-Ala, or Aib (replacing of hydrogen atoms by methyl groups), were applied to obtain octa- and heptapeptide analogues of α-MSH(4-11) and α-MSH(5-11), which were cyclized by lactam bridges between the side chains in positions 5 and 11. Some of these analogues, namely those with substitutions of the Gly10 residue with L-Ala or Aib, showed biological activity potencies on frog skin comparable to the potency of the parent tridecapeptide hormone. Additional energy calculations for designed cyclic analogues were used for further refinement of the model for the biologically active conformations of the His-Phe-Arg-Trp “message” sequence within the sequences of α-MSH and [D-Phe7]α-MSH. In such conformations the aromatic moieties of the side chains of the His6, L/D-Phe7, and Trp9 residues form a continuous hydrophobic “surface,” presumably interacting with a complementary receptor site. This feature is characteristic for low-energy conformers of active cyclic analogues, but it is absent in the case of inactive analogues. This particular spatial arrangement of functional groups involved in the message sequence is very close for α-MSH and [D-Phe7]α-MSH, as well as for biologically active cyclic analogues despite differences of dihedral angle values for corresponding low-energy conformations. © 1998 John Wiley & Sons, Inc. Biopoly 46: 155-167, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Raman spectral study of solid and dissolved poly(vinyl alcohol) and ethylene-vinyl alcohol copolymer (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 1163-1174 
    Details
    ISSN: 0887-6266
    Keywords: poly(vinyl alcohol) ; raman spectroscopy ; polymer ; aqueous solution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We have measured the Raman spectra of ethylene-vinyl alcohol copolymer (EVOH) and poly(vinyl alcohol) (PVOH). Spectra of 88% hydrolyzed PVOH were examined from the partially crystalline solid, from PVOH dissolved in both H2O and D2O, and from films precipitated from these solutions. The spectrum in H2O differs from that of the starting material by disappearance of sharp bands having Raman shift values of 1146 and 1093 cm-1, strengthening of a band near 915 cm-1, decrease in frequency of bands at 480, 1356, and 1441 cm-1, and increase in frequency of bands at 369, 413, 1023, 1371, and 2910 cm-1. The spectrum of the film shows partial reversal of these trends. With D2O as the solvent, the band shifts are slightly different from those listed above and new bands appear. These changes are indicative of loss of crystallinity, change in stereochemistry, and partial deuteration of hydroxyl during dissolution of this PVOH sample at room temperature. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090320704
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  • 8
    Electronic Resource
    Electronic Resource
    On the thickness and spatial distribution of a fluoropolymer film deposited by solution dipping (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 211-222 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly-1H,1H-pentadecafuorooctyl methacrylate is a barrier compound used to prevent silicone oil from creeping to relay contacts. It is essentially a methyl methacrylate polymer with a fluorocarbon side chain substituted for one of the methyl hydrogens. It is applied by dipping the part into a solution, with Freon TF as the solvent and the fluorocarbon polymer as the solute. This work considers the spatial distribution of the resulting film of barrier compound when it is deposited in this manner. The specific variables considered are concentration and withdrawal velocity. The samples were withdrawn from the solution with velocity perpendicular to the surface, and we show that the macrosopic uniformity and thickness of the film is dependent on this velocity. There exists a critical velocity (dependent on concentration) above which the film is nonuniform and below which the film is macroscopically uniform. Below the critical velocity, the thickness varies with velocity with approximately a v2/3 dependence. The critical velocity is about 13 mm/sec for a concentration of 0.2%. For macroscopically uniform films, a microscopic nonunitormity exists with a coverage of about 1/4 for an average film thickness of 90 Å.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1980.070250207
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of stretching conditions on properties of amorphous polyethylene terephthalate film (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 2231-2247 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of stretching condition on stress-induced crystallization of amorphous polyethylene terephthalate (PET) film has been studied. Cast PET film was stretched at 85°C with stretching rates ranging from 100% per minute to 600% per minute for various stretching ratios. The stretched film samples were annealed at 140°C both under tension as well as under relaxed conditions. Tensile properties were determined using Instron Tensile Tester and results were compared. Tenacity, yield stress, and initial modulus were found to increase while elongation at break decreased with the increase in stretching rate. The degree of crystallinity was measured by x-ray diffraction as well as density methods. Birefringence and crystalline orientation factor values were determined experimentally and using these, amorphous orientation factor values were calculated. Birefringence, crystalline orientation and amorphous orientation values were found to increase with the increase in stretching rate. These studies showed that at low stretching rates a significant amount of relaxation takes place, resulting in lower orientation and strength. On the other hand, at higher stretching rates relaxation is minimized thus providing high orientation and strength. Upon annealing the crystallinity values increased as expected, however the trend of orientation and mechanical properties with respect to stretching rate was similar to those of unannealed films.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070340615
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of thermal treatment on the electrothermographic and electrical properties of poly(acrylonitrile butadiene styrene) (1985)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 130 (1985), S. 91-97 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden Untersuchungen zum elektrothermographischen und zum Leitfähigkeitsverhalten von Poly(Acrylnitril-Butadien-Styrol) (ABS) nach unterschiedlichen thermischen Vorbehandlungen durchgeführt. Die spezifischen Widerstände von bei 50°C gelagerten ABS-Platten erwiesen sich als klein (∼ 1015 Ω · cm). Auch die Ladungsaufnahme und die Ladungsspeicherung waren schlecht. Der Grund dafür ist die Adsorption von Wassermolekülen. Werden die Platten bei 100°C oder mehr für 5 h thermisch beansprucht, zeigen sie erhöhte spezifische Widerstände (∼ 1017 Ω· cm bei 50°C) und haben deshalb eine bessere Ladungsaufnahme und -speicherung. Sowohl Umwelt- und Lagerungsbedingungen als auch eine thermische Behandlung während der Herstellung der Platten haben unterhalb 110°C keinen Einfluß auf die Temperaturabhängigkeit der spezifische Widerstände.
    Notes: Studies on the electrothermographic and conductivity behaviour of poly(acrylonitrile butadiene styrene) (ABS) films of different thermal pretreatments were carried out. The resistivity in ABS layers stored at 50°C was found to be low (∼ 1015 Ω · cm). The charge acceptance and its retention also is poor. The reason for that is the adsorption of water molecules. The layers, when thermally treated at 100°C or more for 5 h, show an enhanced resistivity (∼ 1017 Ω · cm at 50°C) and hence an improvement in charge acceptance as well as in charge retention. Environmental and storage conditions as well as thermal treatment during layer preparations have no effect on the temperature dependence of the resistivity beyond 110°C.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1985.051300107
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