@misc{Peter1980,
author = {Peter, Martin G.},
title = {Products of in vitro oxidation of N-acetyldopamine as possible components in the sclerotization of insect cuticle},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16759},
year = {1980},
abstract = {[1-14C]-N-Acetyldopamine (NADA) was oxidized in the presence of methyl [3-3H]-β-alanate with mushroom tyrosinase. The complex mixture of reaction products was partly resolved by chromatographic procedures and analyzed by spectroscopic methods. Methyl-β-alanate is incorporated to only a small extent into oxidation products of NADA which inter alia are presumed to be oligomeric hydroxyquinones. After oxidation of [1-14C, 2-3H]-NADA with preparations from tanning Manduca sexta pupal cuticle, N-acetylnoradrenalin was identified as one of the products. Binding of radioactivity to melanin-like material was also observed. These results suggest that oxidation products different from those formulated usually for the crosslinkages between protein amino groups and N-acetyldopaquinone are deposited in darkly brown coloured insect cuticles during sclerotization.},
language = {en}
}
@misc{FerenzPeterBerg1983,
author = {Ferenz, Hans-J{\"u}rgen and Peter, Martin G. and Berg, Dieter},
title = {Inhibition of farnesoic acid methyltransferase by sinefungin},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17016},
year = {1983},
abstract = {Sinefungin inhibited the S-adenosylmethionine-dependent farnesoic acid methyltransferase in a cell-free system containing a homogenate of corpora allata from female locusts, Locusta migratoria. The enzyme catalyzed the penultimate step of juvenile hormone biosynthesis in the insects. Culturing corpora allata in the presence of sinefungin greatly suppressed juvenile hormone production. The following in vivo effects were visible after injection of the inhibitor: increase in mortality and reduction of total haemolymph protein liter and ovary fresh weight, as well as length of terminal oocytes. Attempts to reverse these effects by topical application of the juvenile hormone analog ZR-515 (methoprene) were only partly successful. Therefore, the in vivo effects may be due to a general inhibition of methyltransferase enzymes in the insect. Sinefungin appeared to be of potential interest as the first representative of a new class of insect growth regulators.},
language = {en}
}
@misc{KortPeterKoopmanschap1983,
author = {Kort, C. A. D. de and Peter, Martin G. and Koopmanschap, A. B.},
title = {Binding and degradation of juvenile hormone III by haemolymph proteins of the Colorado potato beetle: a re-examination},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16777},
year = {1983},
abstract = {The haemolymph of the adult Colorado potato beetle, Lepinotarsa decemlineata Say, contains a high molecular weight (MW > 200,000) JH-III specific binding protein. The Kd value of the protein for racemic JH-III is 1.3 ± 0.2 × 10-7 M. It has a lower affinity for racemic JH-I and it does not bind JH-III-diol or JH-III-acid. The binding protein does discriminate between the enantiomers of synthetic, racemic JH-III as was determined by stereochemical anaysis of the bound and the free JH-III. Incubation of racemic JH-III with crude haemolymph results in preferential formation of (10S)-JH-III-acid, the unnatural configuration. The JH-esterase present in L. decemlineata haemolymph is not enantioselective. It is concluded that the most important function of the binding protein is that of a specific carrier, protecting the natural hormone against degradation by esterases. The carrier does not protect JH-I as efficiently as the lower homologue.},
language = {en}
}
@misc{LaschewskyRingsdorfSchmidt1985,
author = {Laschewsky, Andr{\´e} and Ringsdorf, H. and Schmidt, G.},
title = {Polymerization of hydrocarbon and fluorocarbon amphiphiles in Langmuir-Blodgett multilayers},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17096},
year = {1985},
abstract = {Langmuir-Blodgett multilayers of polymerizable carboxylic acids with hydrocarbon or fluorocarbon chains were prepared. The multilayers were polymerized by UV light and the reactions were studied by UV/visible spectroscopy. The polyreactions strongly influence the multilayer structures which were investigated by X-ray small-angle scattering and scanning electron microscopy. The spreading behaviour of the monomers, the preparation of multilayers, their reactivities in multilayers and structural effects caused by the polyreactions are discussed with regard to the hydrophilic head groups, the polymerizable groups and the hydrophobic chains.},
language = {en}
}
@misc{ElbertLaschewskyRingsdorf1985,
author = {Elbert, R. and Laschewsky, Andr{\´e} and Ringsdorf, H.},
title = {Hydrophilic spacer groups in polymerizable lipids: formation of biomembrane models from bulk polymerized lipids},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17361},
year = {1985},
abstract = {A variety of polymerizable lipids containing a hydrophilic spacer group between the reactive group and the main amphiphilic structure have been synthesized. They were investigated in monolayers, liposomes, and multilayers. When the spacer concept was used, efficient decoupling of the motions of the polymeric chain and the amphiphilic side groups is achieved. Thus, the often found loss of the important fluid phases by polymerization is avoided. Polymeric monolayers of the spacer lipid, prepared either by polymerization in the monolayer or by spreading of prepolymerized lipid, exhibit nearly identical surface pressure-area diagrams. Most distinctly, the successful decoupling of the motions of the polymer main chain and the membrane forming amphiphilic side groups is demonstrated by the self-organization of bulk polymerized spacer lipids to polymeric liposomes. In addition, spacer lipids are able to build polymeric Langmuir-Blodgett multilayers. The decoupling of the polymer main chain and the membrane-forming amphiphilic side groups enables the deposition of already polymeric monolayers onto supports to form defined multilayers. If, alternatively, monomeric monolayers are deposited and polymerized on the support, defects in the layers due to structural changes during the polymerization are avoided by the flexible spacer group.},
language = {en}
}
@misc{KochLaschewskyRingsdorfetal.1986,
author = {Koch, Horst and Laschewsky, Andr{\´e} and Ringsdorf, Helmut and Teng, Kang},
title = {Photodimerization and photopolymerization of amphiphilic cinnamic acid derivatives in oriented monolayers, vesicles and solution},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17111},
year = {1986},
abstract = {Cinnamic acid moieties were incorporated into amphiphilic compounds containing one and two alkyl chains. These lipid-like compounds with photoreactive units undergo self-organization to form monolayers at the gas-water interface and bilayer structures (vesicles) in aqueous solutions. The photoreaction of the cinnamic acid moiety induced by 254 nm UV light was investigated in the crystalline state, in monolayers, in vesicles and in solution in organic solvents. The single-chain amphiphiles undergo dimerization to yield photoproducts with twice the molecular weight of the corresponding monomers in organized systems. The photoreaction of amphiphiles containing two cinnamic acid groups occurs via two mechanisms: The intramolecular dimerization produces bicycles, with retention of the molecular weight of the corresponding monomer. The intermolecular reaction leads to oligomeric and polymeric photoproducts. In contrast to the single-chain amphiphiles, photodimerization processes of lipoids containing two cinnamic acid moieties also occur in solution in organic solvents.},
language = {en}
}
@misc{AlbrechtCummingKreuderetal.1986,
author = {Albrecht, O. and Cumming, W. and Kreuder, W. and Laschewsky, Andr{\´e} and Ringsdorf, Helmut},
title = {Monolayers of rod-shaped and disc-shaped liquid crystalline compounds at the air-water interface},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17124},
year = {1986},
abstract = {Calamitic (rod-shaped) and discotic (disc-shaped) thermotropic liquid crystalline (LC) compounds were spread at the air-water interface, and their ability to form monolayers was studied. The calamitic LCs investigated were found to form monolayers which behave analogously to conventional amphiphiles such as fatty acids. The spreading of the discotic LCs produced monolayers as well, but with a behaviour different from classical amphiphiles. The areas occupied per molecule are too small to allow the contact of all hydrophilic groups with the water surface and the packing of all hydrophobic chains. Various molecular arrangements of the discotics at the water surface to fit the spreading data are discussed.},
language = {en}
}
@misc{LaschewskyRingsdorfSchneider1986,
author = {Laschewsky, Andr{\´e} and Ringsdorf, H. and Schneider, J.},
title = {Oriented supramolecular systems-polymeric monolayers and multilayers from prepolymerized amphiphiles},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17131},
year = {1986},
abstract = {Oriented polymeric membranes were originally prepared by polymerization or polycondensation of preoriented monomers. The introduction of hydrophilic spacer groups into the polymeric amphiphiles allowed the formation of highly ordered systems (monolayers, liposomes, multilayers) from prepolymerized amphiphiles: due to the partial decoupling of the different mobilities and orientation tendencies of the polymer chain and the amphiphilic side groups, these polymers are able to self-organize. In monolayer experiments the high order of these membranes could be demonstrated by their surface pressure area-diagrams. In addition the combination of order and mobility of these spacer groups containing polymeric amphiphiles allowed the formation of Langmuir-Blodgett-multilyers with a high layer correlation. Thus, disturbancies in highly oriented layers can be avoided normally taking place during the polymerization reaction (e.g. contractions) or oriented monomeric layers.},
language = {en}
}
@misc{LaschewskyRingsdorfSchmidtetal.1987,
author = {Laschewsky, Andr{\´e} and Ringsdorf, H. and Schmidt, G. and Schneider, J.},
title = {Self-organization of polymeric lipids with hydrophilic spacers in side groups and main chain : investigation in monolayers and multilayers},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17147},
year = {1987},
abstract = {Several polymerizable lipids were synthesized and polymerized to amphiphilic homopolymers and to copolymers with the help of hydrophilic comonomers. The self-organization of these polymeric lipids was investigated in monolayers and Langmuir-Blodgett multilayers. The self-organization of these polymers in model membranes is due to hydrophilic spacer groups in the amphiphilic side groups as well as to hydrophilic spacer groups in the polymer backbone. Thus, highly ordered monolayers and LB-multilayers are easily obtained.},
language = {en}
}
@misc{FerenzPeter1987,
author = {Ferenz, Hans-J{\"o}rg and Peter, Martin G.},
title = {The inhibitory effect of sinefungin on juvenile hormone biosynthesis and development in locusts},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16811},
year = {1987},
abstract = {The antibiotic fungal metabolite sinefungin is a potent inhibitor of S-adenosylmethionine-acceptor methyltransferases. Its effect on insect metabolism and especially on corpora allata farnesoic acid methyltransferase, which catalyzes the penultimate step of juvenile hormone biosynthesis, was investigated in Locusta migratoria. Injection of sinefungin results in a delay of imaginal molt and in suppression of ovary development. Isolated corpora allata are unable to synthesize juvenile hormone III in the presence of more than 1.0 mM sinefungin. In a cell-free system containing the S-adenosylmethionine-dependent farnesoic acid methyltransferase from corpora allata sinefungin is a competitive inhibitor of the synthesis of methylfarnesoate with Ki of 1 μM.},
language = {en}
}
@misc{LaschewskyRingsdorf1988,
author = {Laschewsky, Andr{\´e} and Ringsdorf, H.},
title = {Polymerization of amphiphilic dienes in Langmuir-Blodgett multilayers},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17176},
year = {1988},
abstract = {Amphiphilic derivatives of octadiene and docosadiene were investigated in monolayers and Langmuir-Blodgett multilayers, with respect to their self-organization and their polymerization behavior. All amphiphiles investigated form monolayers. However, only acid and alcohol derivatives were able to build up multilayers. Those multilayers are rapidly photopolymerized in the layers via a two-step process: Irradiation with long-wavelength UV light yields soluble polymers, whereas additional irradiation with sfiort-wavelength UV light produces insoluble and presumably cross-linked polymers. The reaction meclianism is discussed according to the polymer characterization by UV spectroscopy, small-angle X-ray scattering, NMR spectroscopy, and gel permeation chromatography. All multilayers undergo structural changes during the polymerization; substantial changes result in defects in the polymerized layers as observed by scanning electron microscopy. In contrast to the acids and alcohols, the deposition of monolayers of the aldehyde derivatives did not yield well-ordered multilayers, but rather amorphous films. In this different film structure, the photopolymerization process differs from the one observed in multilayers.},
language = {en}
}
@misc{LupoPrassScheunemannetal.1988,
author = {Lupo, Donald and Prass, Werner and Scheunemann, Ude and Laschewsky, Andr{\´e} and Ringsdorf, Helmut and Ledoux, Isabelle},
title = {Second-harmonic generation in Langmuir-Blodgett monolayers of stilbazium salt and phenylhydrazone dyes},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17401},
year = {1988},
abstract = {Contents: 1. INTRODUCTION 2. SYNTHESIS OF THE COMPOUNDS 3. PREPARATION AND CHARACTERIZATION OF MONOLAYERS A. Monolayer Isotherms B. Langmuir-Blodgett Monolayer Films 4. EXPERIMENTAL SETUP FOR NONLINEAR MEASUREMENTS 5. NONLINEAR OPTICAL PROPERTIES 6. DISCUSSION 7. CONCLUSION},
language = {en}
}
@misc{PeterFoerster1989,
author = {Peter, Martin G. and F{\"o}rster, Hans},
title = {On the structure of Eumelanins : identification of constitutional patterns by solid-state NMR spectroscopy},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17027},
year = {1989},
abstract = {Aus dem Inhalt: Melanins are complex polyphenolic polymers. They are usually formed in nature by enzyme-catalyzed oxidative polymerization of o-diphenols. The deep black eumelanins, derived from Dopa 1 or dopamine 3, are distinguished from the yellow to brown phaeomelanins obtained from Dopa in the presence of cysteine. Characteristic of eumelanins are the indole units, which are formed from catecholamines by intramolecular addition of the amino groups to the oxidatively generated o-quinones. [...]},
language = {en}
}
@misc{ErdelenLaschewskyRingsdorfetal.1989,
author = {Erdelen, C. and Laschewsky, Andr{\´e} and Ringsdorf, H. and Schneider, J. and Schuster, A.},
title = {Thermal behaviour of polymeric Langmuir-Blodgett multilayers},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17378},
year = {1989},
abstract = {Langmuir-Blodgett multilayers of hydrocarbon and fluorocarbon polymers with hydrophilic spacer, lipid-polyelectrolyte complexes and mesogenic polymers have been prepared. The thermal behaviour of the multilayers was studied by small angle X-ray scattering, IR and UV—visible spectroscopy. Good thermal stabilities were found for the various classes of polymers. In addition, for both complexed multilayers and mesogenic polymer films, reorientation processes were observed.},
language = {en}
}
@misc{Laschewsky1989,
author = {Laschewsky, Andr{\´e}},
title = {Monolayers and Langmuir-Blodgett multilayers of discotic liquid crystals?},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17396},
year = {1989},
abstract = {Contents: 1. Discotic Liquid Crystals 2. Monolayers and Langmuir-Blodgett Multilayers 3. Theoretical Considerations on the Molecular Packing of Discotic LCs in Monolayers and Multilayers 4. Spreading Experiments with Discotic LCs 5. LB-Multilayers of Discotic LCs 6. Polymeric Discotic LCs 7. Summary},
language = {en}
}
@misc{BiddleRickertLandoetal.1989,
author = {Biddle, M. B. and Rickert, S. E. and Lando, J. B. and Laschewsky, Andr{\´e}},
title = {The use of the Langmuir-Blodgett technique to obtain ultra-thin polar films},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17185},
year = {1989},
abstract = {The piezoelectric and pyroelectric properties of oriented films possessing dipole moments are increasingly being used in pressure, acoustic, thermal and optical devices. The performance of these devices in many applications may be enhanced by thin-film technology.The developing Langmuir-Blodgett thin-film deposition technique offers the opportunity to obtain highly oriented and uniform organic-based films in the 10-5000 nm thickness range. Special techniques must be used, however, to assemble these molecules in such a way as to result in polar multilayer films. Several possible deposition techniques are investigated, with one resulting in a polar and pyroelectric film about 50 nm thick.},
language = {en}
}
@misc{EmbsFunhoffLaschewskyetal.1991,
author = {Embs, Frank and Funhoff, Dirk and Laschewsky, Andr{\´e} and Licht, Ulrike and Ohst, Holger and Prass, Werner and Ringsdorf, Helmut and Wegner, Gerhard and Wehrmann, Rolf},
title = {Preformed polymers for Langmuir-Blodgett films- molecular concepts},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17196},
year = {1991},
abstract = {The use of preformed polymers for the preparation of Langmuir-Blodgett (LB) multilayers is reviewed. Principles for polymer self-organization are outlined and the appropriate molecular designs are discussed. Recent developments in the different classes of polymers for LB multilayers are presented, and their outstanding properties highlighted.},
language = {en}
}
@misc{BubeckLaschewskyLupoetal.1991,
author = {Bubeck, Christoph and Laschewsky, Andr{\´e} and Lupo, Donald and Neher, Dieter and Ottenbreit, Petra and Paulus, Wolfgang and Prass, Werner and Ringsdorf, Helmut and Wegner, Gerhard},
title = {Amphiphilic dyes for nonlinear optics: Dependence of second harmonic generation on functional group substitution},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17201},
year = {1991},
language = {en}
}
@misc{AntonLaschewsky1991,
author = {Anton, Peter and Laschewsky, Andr{\´e}},
title = {Polysoaps via alternating olefin/SO2 copolymers},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17216},
year = {1991},
abstract = {Contents: Introduction Results and discussion - Monomers studied - Monomer properties - Polymerization, copolymer composition and general properties - Polymer properties in aqueous solution Conclusion Experimental part - Materials - Copolymerization with S02 (typical procedure) - Methods},
language = {en}
}
@misc{Laschewsky1991,
author = {Laschewsky, Andr{\´e}},
title = {Oligoethyleneoxide spacer groups in polymerizable surfactants},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17221},
year = {1991},
abstract = {Cationic and zwitterionic polymerizable surfactants bearing tri- and tetraethyleneglycol spacer groups between the polymerizable moiety and the surfactant structure were prepared and polymerized. Monomers and polymers were investigated with respect to their aggregation behavior in aqueous systems and compared to analogous monomers and polymers lacking spacer groups. In the case of the monomeric surfactants, the spacer groups depress both the Kraffttemperature and the critical micelle concentration. the area occupied per molecule at the air-water interface is substantially enlarged by the spacers, whereas the depression of surface tension is nearly constant. Although the monomers with and without spacers are true surfactants, all the polymers are water-insoluble, but form monomolecular layers at the air-water interface. In analogy to the monomer behavior, the incorporation of the spacer groups increases the area occupied per repeat unit at the air-water interface substantially, but hardly affects the surface activity.},
language = {en}
}
@misc{KoeberleLaschewskyTsukruk1992,
author = {K{\"o}berle, Peter and Laschewsky, Andr{\´e} and Tsukruk, Vladimir},
title = {The structural order of some novel ionic polymers : 1. X-ray scattering studies},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17247},
year = {1992},
abstract = {A set of novel zwitterionic side-chain polyacrylates and polymethacrylates is studied by X-ray scattering. The structural order both in the short-range and long-range scale is investigated. The influence of the polymer backbone, of different locations of the ionic groups in isomeric polymers, of bound water and of added inorganic salts on the bulk structures is studied, and the observed rearrangements are analysed.},
language = {en}
}
@misc{PeterAndersenHartmannetal.1992,
author = {Peter, Martin G. and Andersen, Svend Olav and Hartmann, Rudolf and Miessner, Merle and Roepstorff, Peter},
title = {Catecholamine-protein conjugates : isolation of 4-phenylphenoxazin-2-ones from oxidative coupling of N-acetyldopamine with alipathic amino acids},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17571},
year = {1992},
abstract = {4-Phenylphenoxazinones were isolated after biomimetic oxidation, using diphenoloxidases of insect cuticle, mushroom tyrosinase, or after autoxidation of N-acetyldopamine (Image ) in the presence of β-alanine, β-alanine methyl ester or N-acetyl-L-lysine. They are formed presumably by addition of 2-aminoalkyl-5-alkylphenols to the o-quinone of biphenyltetrol which, in turn, arises from oxidative coupling of. The structures of present the first examples for the assembly of reasonably stable intermediates in the rather complex process of chemical modifications of aliphatic amino acid residues by o-quinones.},
language = {en}
}
@misc{LaschewskyPaulusRingsdorfetal.1992,
author = {Laschewsky, Andr{\´e} and Paulus, Wolfgang and Ringsdorf, Helmut and Schuster, A. and Frick, G. and Mathy, A.},
title = {Mixed polymeric monolayers and Langmuir-Blodgett multilayers with functional low molecular weight guest compounds},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17233},
year = {1992},
abstract = {Mixed monolayers and Langmuir-Blodgett multilayers of functional low molecular weight guest compounds, especially nonlinear optical (NLO) dyes, within the matrix of an amphotropic spacer polymer have been prepared. The polymer matrix enabled the transfer of guest compounds not capable of self-organizing at the air-water interface by themselves. The structure of the LB multilayers and the transfer process were studied by small angle X-ray scattering and UV-visible spectroscopy. Good NLO coefficients were found in the mixed films.},
language = {en}
}
@misc{AndersenPerterRoepstorff1992,
author = {Andersen, Svend Olav and Perter, Martin G. and Roepstorff, Peter},
title = {Cuticle-catalyzed coupling between N-acetylhistidine and N-acetyldopamine},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16762},
year = {1992},
abstract = {Several types of insect cuticle contain enzymes catalyzing the formation ofof adducts between N-acetyldopamine (NADA) and N-acetylhistidine (NAH). Two such adducts, NAH-NADA-I and NAH NADA-II, have been isolated and their structures determined. In one of the adducts the link connecting the two residues occurs between the I-position (ß-position) in the NADA side chain and the 1-N atom (τ-N) in the imidazole ring of histidine. Diphenoloxidase activity alone is not sufficient for formation of this adduct, whereas extracts containing both diphenoloxidase and o-quinone-p-quinone methide isomerase activities catalyze the coupling reaction. The adduct consists of a mixture of two diastereomers and they are presumably formed by spontaneous reaction between enzymatically produced NADA-p-quinone methide and N-acetylhistidine. The other adduct has been identified as a ring addition product of N-acetylhistidine and NADA. In contrast to the former adduct it can be formed by incubation of the two substrates with mushroom tyrosinase alone. An adduct between N-acetylhistidine and the benzodioxan-type NADA-dimer is produced in vitro, when the N-acetylhistidine-NADA adduct is incubated with NADA and locust cuticle containing a 1,2-dehydro-NADA generating enzyme system. Trimeric NADA-polymerization products of the substituted benzodioxan-type have been obtained from in vivo sclerotized locust cuticle, confirming the ability of cuticle to produce NADA-oligomers. The results indicate that some insect cuticles contain enzymes promoting linkage of oxidized NADA to histidine residues. It is suggested that histidine residues in the cuticular proteins can serve as acceptors for oxidized NADA and that further addition of NADA-residues to the phenolic groups of bound NADA can occur, resulting in formation of protein-linked NADA-oligomers. The coupling reactions identified may be an important step in natural cuticular sclerotization.},
language = {en}
}
@misc{TsukrukMischenkoKoeberleetal.1992,
author = {Tsukruk, Vladimir and Mischenko, Nikolay and K{\"o}berle, Peter and Laschewsky, Andr{\´e}},
title = {The structural order of some novel ionic polymers; 2. : Models of molecular packing},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17256},
year = {1992},
abstract = {The molecular packing and spatial correlations of two isomeric zwitterionic polymethacrylates and one polyacrylate analog are studied by means of X-ray analysis and conformational calculations. The analysis of the correlation functions and density distribution profiles suggest a double-layered molecular packing which is discussed for the three polymers investigated, with respect to their different chemical structures. Whereas the zwitterionic polymethacrylates studied exhibit liquid-like short-range order, the polyacrylate analog exhibits an ordered double-layered superstructure.},
language = {en}
}
@misc{AntonLaschewsky1993,
author = {Anton, Peter and Laschewsky, Andr{\´e}},
title = {Zwitterionic polysoaps with reduced density of surfactant side groups},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17301},
year = {1993},
abstract = {Several zwitterionic polymers were prepared by radical homopolymerization of surfactant monomers which bear diallyl, diene or vinylcyclopropane moieties. These polymer systems were complemented by alternating copolymers of appropriate zwitterionic vinyl compounds. Thus, polymers with reduced (as compared with simple vinylic homopolymers, or statistical copolymers) and well defined density of surfactant side groups are obtained. The solubilities found for these polymers are dominated by polymer geometry rather than by the balance of hydrophilic and hydrophobic fragments, thus corroborating a main-chain spacer model proposed recently. All water-soluble polymers exhibit characteristic features of classical polysoaps, as shown by surface tension measurements and by solubilization of hydrophobic dyes. In contrast, the water-insoluble copolymers are capable to form stable monolayers at the air-water interface.},
language = {en}
}
@misc{AntonKoeberleLaschewsky1993,
author = {Anton, Peter and K{\"o}berle, Peter and Laschewsky, Andr{\´e}},
title = {Recent developments in the field of micellar polymers},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17263},
year = {1993},
abstract = {This article describes recent achievements in the field of micellar polymers, or polysoaps. Taking advantage of zwitterionic model polymers, systematic variations of the molecular architecture have provided an improved understanding of the relationship between the molecular structure of the polymers and their key properties such as surface activity and solubilization capacity. Useful rules are established, which take into account much of the previous data in the literature.},
language = {en}
}
@misc{LaschewskySchulzHanke1993,
author = {Laschewsky, Andr{\´e} and Schulz-Hanke, Wolfgang},
title = {Ring-opening metathesis polymerization of amphiphilic norbornenes functionalized with non-linear optical (NLO) chromophores},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26917},
year = {1993},
abstract = {Contents: Potential of amphiphilic NLO polymers Ring-opening metathesis polymerization (ROMP) Properties of the polymers Monolayer properties Experimental part - Methods - Materials - Analytical data - General polymerization procedure Conclusions},
language = {en}
}
@misc{KoeberleLaschewsky1994,
author = {K{\"o}berle, Peter and Laschewsky, Andr{\´e}},
title = {Hybrid materials from organic polymers and inorganic salts},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26884},
year = {1994},
abstract = {The prepaparation of amorphous, homogeneous blends of zwitterionic polymers and transition metal salts was investigated. Homogeneous miscibility was achieved in many cases up to equimolar amounts of salt, depending on the anion and cation chosen. Various analytical techniques point to a solid state solution of the inorganic ions in the polymer matrix.},
language = {en}
}
@misc{AntonLaschewsky1994,
author = {Anton, Peter and Laschewsky, Andr{\´e}},
title = {Solubilization by polysoaps},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17327},
year = {1994},
abstract = {The aqueous solubilization power of several series of micellar homopolymers and copolymers (polysoaps) is investigated. Using five insoluble or poorly water-soluble dyes, comparisons of the capacities are made with respect ot the influence of structural variables such as the polymer backbone, the polymer geometry, the comonomer content, and the charge of the hydrophilic group. Some guidelines for polysoap structures suited for efficient solubilization are established. Noteworthy is that the solubilization capacities of the polysoaps are neither linked to the ability to reduce the surface tension of water, nor to the polarity of the solubilization sites deduced from spectroscopic probes.},
language = {en}
}
@misc{AntonLaschewskyWard1995,
author = {Anton, Peter and Laschewsky, Andr{\´e} and Ward, M. D.},
title = {Solubilization control by redox-switching of polysoaps},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17336},
year = {1995},
abstract = {Reversible changes in the self-organization of polysoaps may be induced by controlling their charge numbers via covalently bound redox moieties. This is illustrated with two viologen polysoaps, which in response to an electrochemical stimulus, change their solubility and aggregation in water, leading from homogeneously dissolved and aggregated molecules to collapsed ones and vice verse. Using the electrochemical quartz crystal microbalance (EQCM), it could be shown that the reversibility of this process is better than 95\% in 16 cycles.},
language = {en}
}
@misc{CochinHendlingerLaschewsky1995,
author = {Cochin, Didier and Hendlinger, P. and Laschewsky, Andr{\´e}},
title = {Polysoaps with fluorocarbon hydrophobic chains},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17347},
year = {1995},
abstract = {A series of amphiphilic copolymers is prepared by copolymerization of choline methacrylate with 1,1,2,2-tetrahydroperfluorooctyl methacrylate in varying amounts. The copolymers bearing fluorocarbon chains are studied concerning their effects on viscosity, solubilization and surface activity in aqueous solution, exhibiting a general behavior characteristic for polysoaps. The results are compared with the ones obtained for an analogous series of amphiphilic copolymers bearing hydrocarbon chains.},
language = {en}
}
@misc{Laschewsky1995,
author = {Laschewsky, Andr{\´e}},
title = {Molecular concepts, self-organisation and properties of polysoaps},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26895},
year = {1995},
abstract = {The article reviews water-soluble polymers characterized by surfactant side chains, and related amphiphilic polymers. Various synthetic approaches are presented, and rules for useful molecular architectures are given. Models for the self-organization of such polymers in water are presented comparing them with the micellization of low molecular weight surfactants. Highlighting key properties of aqueous polysoap solutions such as viscosity, surface tension and solubilization power, some structure-property relationships are established. Further, the formation of mesophases and of superstructures in bulk is addressed. Finally, the functionalization of polysoaps, and potential applications are discussed.},
language = {en}
}
@misc{RozanskiKremerKoeberleetal.1995,
author = {Rozanski, Stanislaw A. and Kremer, Friedrich and K{\"o}berle, Peter and Laschewsky, Andr{\´e}},
title = {Relaxation and charge transport in mixtures of zwitterionic polymers and inorganic salts},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17438},
year = {1995},
abstract = {Dielectric spectroscopy is employed to analyze the molecular dynamics and the charge transport in mixtures of zwitterionic polymers of the type poly{3 [N(-methacryloyloxyalkyl)] N, [N-dimethylammonio propanesulfonate] with sodium iodide in the frequency range of 10²Hz-10(up)7 Hz and in the temperature range of 110 K-400 K. The amount of inorganic salt added varies from 0-200 mol-\% relative to the number of zwitterionic groups present in the polymer, contributing strongly to the conductivity. One relaxation process is observed whose relaxation rate depends strongly on the length of the aliphatic spacer between the polymethacrylate main chain and the zwitterionic group. Exhibiting an Arrhenius-like temperature depence with activation energy EA = 47 KJ/mol, this relaxation process is assigned to fluctuation of the quaternary ammonium groups in the side chains. At higher temperatures, the dielectric properties and the conductivity are primarily dominated by the mobile inorganic ions: conductivity strongly depends on the salt concentration, showing a pronounced electrode polarization effect. The frequency and salt concentration, dependences of the conductivity can be quantitatively described as hopping of charge carriers being subject to spatially randomly varying energy barriers. For the low-frequency regime and for the critical frequency marking the onset of the conductivity's dispersion, the Barton-Nakajima-Namikawa (BNN) relationship is fulfilled.},
language = {en}
}
@misc{KumkeFrimmel2002,
author = {Kumke, Michael Uwe and Frimmel, Fritz Hartmann},
title = {Stationary and time-resolved fluorescence for humic substances characterization},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12353},
year = {2002},
abstract = {Steady-state and time-resolved fluorescence methods were applied to investigate the fluorescence properties of humic substances of different origins. Using standard 2D emission and total luminescence spectra, fluorescence maxima, the width of the fluorescence band and a relative fluorescence quantum efficiency were determined. Different trends for fulvic acids and humic acids were observed indicating differences in the heterogeneity of the sample fractions. The complexity of the fluorescence decay of humic substances is discussed and compared to simple model compounds. The effect of oxidation of humic substances on their fluorescence properties is discussed as well.},
language = {en}
}
@misc{DoscheLoehmannsroebenBieseretal.2002,
author = {Dosche, Carsten and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Bieser, A. and Dosa, P. I. and Han, S. and Iwamoto, M. and Schleifenbaum, A. and Vollhardt, K. Peter C.},
title = {Photophysical properties of [N]phenylenes},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-11936},
year = {2002},
abstract = {In the present study, photophysical properties of [N]phenylenes were studied by means of stationary and time-resolved absorption and fluorescence spectroscopy (in THF at room temperature). For biphenylene (1) and linear [3]phenylene (2a), internal conversion (IC) with quantum yields ΦIC > 0.99 is by far the dominant mechanism of S1 state deactivation. Angular [3]phenylene (3a), the zig-zag [4]- and [5]phenylenes (3b), (3c), and the triangular [4]phenylene (4) show fluorescence emission with fluorescence quantum yieds and lifetimes between ΦF = 0.07 for (3a) and 0.21 for (3c) and τF = 20 ns for (3a) and 81 ns for (4). Also, compounds (3) and (4) exhibit triplet formation upon photoexcitation with quantum yields as high as ΦISC = 0.45 for (3c). The strong differences in the fluorescence properties and in the triplet fromation efficiencies between (1) and (2a) on one hand and (3) and (4) on the other are related to the remarkable variation of the internal conversion (IC) rate constants kIC. A tentative classification of (1) and (2a) as "fast IC compounds", with kIC > 109 s-1, and of (3) and (4) as "slow IC compounds", with kIC ≈ 107 s-1, is suggested. This classification cannot simply be related to H{\"u}ckel's rule-type concepts of aromaticity, because the group of "fast IC compounds" consists of "antiaromatic" (1) and "aromatic" (2a), and the group of "slow IC compounds" consists of "antiaromatic" (3b), (4) and "aromatic" (3a), (3c). The IC in the [N]phenylenes is discussed within the framework of the so-called energy gap law established for non-radiative processes in benzenoid hydrocarbons.},
language = {en}
}
@misc{KaafaraniWexStrehmeletal.2002,
author = {Kaafarani, Bilal R. and Wex, Brigitte and Strehmel, Bernd and Neckers, Douglas C.},
title = {Structural concept for fluorinated Y-enynes with solvatochromic properties},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-13168},
year = {2002},
abstract = {An approach to the development of fluorescent probes to follow polymerizations in situ using fluorinated cross-conjugated enediynes (Y-enynes) is reported. Different substitution patterns in the Y-enynes result in distinct solvatochromic behavior. β,β-Bis(phenylethynyl)pentafluorostyrene 7, which bears no donor substituents and only fluorine at the styrene moiety, shows no solvatochromism. Donor substituted β,β-bis(3,4,5-trimethoxyphenylethynyl) pentafluorostyrene 8 and β,β-bis(4-butyl-2,3,5,6-tetrafluorophenylethynyl)-3,4,5-trimethoxystyrene 9 exhibit solvatochromism upon change of solvent polarity. Y-enyne 8 showed the largest solvatochromic shift (94 nm bathochromic shift) upon changing solvent from cyclohexane to acetonitrile. A smaller solvatochromic response (44 nm bathochromic shift) was observed for 9. Lippert-Mataga treatment of 8 and 9 yields slopes of -10,800 and -6,400 cm -1, respectively. This corresponds to a change in dipole moment of 9.6 and 6.9 D, respectively. The solvatochromic behavior in 8 and 9 supports the formation of an intramolecular charge transfer (ICT) state. The low fluorescence quantum yields are caused by competitive double bond rotation. The fluorescence decay time of 9 decreases in methyltetrahydrofuran from 2.1 ns at 77 K to 0.11 ns at 200 K. Efficient single bond rotation in 9 was frozen at -50 °C in a configuration in which the trimethoxyphenyl ring is perpendicular to the fluorinated rings. 7-9 are photostable compounds. The X-ray structure of 7 shows it is not planar and that its conjugation is distorted. Y-enyne 7 stacks in the solid state showing coulombic, actetylene-arene, and fluorine-π interactions.},
language = {en}
}
@misc{BillardAnsoborloAppersonetal.2003,
author = {Billard, Isabelle and Ansoborlo, Eric and Apperson, Kathleen and Arpigny, Sylvie and Azenha, M. Emilia and Birch, David and Bros, Pascal and Burrows, Hugh D. and Choppin, Gregory and Kumke, Michael Uwe},
title = {Aqueous solutions of Uranium(VI) as studied by time-resolved emission spectroscopy : a Round-Robin Test},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12318},
year = {2003},
abstract = {Results of an inter-laboratory round-robin study of the application of time-resolved emission spectroscopy (TRES) to the speciation of uranium(VI) in aqueous media are presented. The round-robin study involved 13 independent laboratories, using various instrumentation and data analysis methods. Samples were prepared based on appropriate speciation diagrams and, in general, were found to be chemically stable for at least six months. Four different types of aqueous uranyl solutions were studied: (1) acidic medium where UO22+aq is the single emitting species, (2) uranyl in the presence of fluoride ions, (3) uranyl in the presence of sulfate ions, and (4) uranyl in aqueous solutions at different pH, promoting the formation of hydrolyzed species. Results between the laboratories are compared in terms of the number of decay components, luminescence lifetimes, and spectral band positions. The successes and limitations of TRES in uranyl analysis and speciation in aqueous solutions are discussed.},
language = {en}
}
@misc{ReichLoehmannsroebenSchael2003,
author = {Reich, Oliver and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Schael, Frank},
title = {Optical sensing with photon density waves: investigation of model media},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-13147},
year = {2003},
abstract = {Investigations with frequency domain photon density waves allow elucidation of absorption and scattering properties of turbid media. The temporal and spatial propagation of intensity modulated light with frequencies up to more than 1 GHz can be described by the P1 approximation to the Boltzmann transport equation. In this study, we establish requirements for the appropriate choice of turbid model media and characterize mixtures of isosulfan blue as absorber and polystyrene beads as scatterer. For these model media, the independent determination of absorption and reduced scattering coefficients over large absorber and scatterer concentration ranges is demonstrated with a frequency domain photon density wave spectrometer employing intensity and phase measurements at various modulation frequencies.},
language = {en}
}
@misc{LoehmannsroebenBeitzLuadienetal.2004,
author = {L{\"o}hmannsr{\"o}ben, Hans-Gerd and Beitz, Toralf and Luadien, Robert and Schultze, Rainer},
title = {Laser-based ion mobility spectrometry for sensing of aromatic compounds},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-11892},
year = {2004},
abstract = {The drift time spectra of polycyclic aromatic hydrocarbons (PAH), alkylbenzenes and alkylphenylethers were recorded with a laser-based ion mobility (IM) spectrometer. The ion mobilities of all compounds were determined in helium as drift gas. This allows the calculation of the diffusion cross sections (Omegacalc) on the basis of the exact hard sphere scattering model (EHSSM) and their comparison with the experimentally determined diffusion cross sections (Omegaexp). These Omegaexp/Omegacalc-correlations are presented for molecules with a rigid structure like PAH and prove the reliability of the theoretical model and experimental method. The increase of the selectivity of IM spectrometry is demonstrated using resonance enhanced multiphoton ionisation (REMPI) at atmospheric pressure, realized by tuneable lasers. The REMPI spectra of nine alkylbenzenes and alkylphenylethers are investigated. On the basis of these spectra, the complete qualitative distinction of eight compounds in a mixture is shown. These experiments are extended to alkylbenzene isomer mixtures.},
language = {en}
}
@misc{HoernerLauLoehmannsroeben2004,
author = {H{\"o}rner, Gerald and Lau, Steffen and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
title = {NIR-diode laser spectroscopy for isotope-selective sensing of soil-respired carbon dioxide},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-10148},
year = {2004},
abstract = {The performance of a home-built tunable diode laser (TDL) spectrometer has been optimized regarding multi-line detection of carbon dioxide in natural gases. In the regime of the (3001)III ← (000) band of 12CO2 around 1.6 μm, the dominating isotope species 12CO2, 13CO2, and 12C18O16O were detected simultaneously. In contrast to most established techniques, selective measurements are performed without any sample preparation. This is possible since the CO2 detection is free of interference from water, ubiquitous in natural gases. Detection limits in the range of a few ppmv were obtained for each species utilizing wavelength modulation (WM) spectroscopy with balanced detection in a long-path absorption cell set-up. Linear calibration plots cover a dynamic range of four orders of magnitude, allowing for quantitative CO2 detection in various samples, like soil and breath gas. High isotopic resolution enables the excellent selectivity, sensitivity, and stability of the chosen analytical concept. The obtained isotopic resolution of typically ± 1.0 per mille and ± 1.5 per mille (for 3 vol. \% and 0.7 vol. \% of CO2, respectively) offers a promising analytical tool for isotope-ratio determination of carbon dioxide in soil gas. Preliminary experiments on soil respiration for the first time combine the on-line quantification of the overall carbon dioxide content with an optode sensor and isotopic determination (TDL system) of natural gas species.},
subject = {Kohlendioxid},
language = {en}
}
@misc{HoernerLauKantoretal.2004,
author = {H{\"o}rner, Gerald and Lau, Steffen and Kantor, Zoltan and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
title = {Isotope selective analysis of CO2 with tunable diode laser (TDL) spectroscopy in the NIR},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-10167},
year = {2004},
abstract = {The performance of a home-built tunable diode laser (TDL) spectrometer, aimed at multi-line detection of carbon dioxide, has been evaluated and optimized. In the regime of the (3001)III / (000) band of 12CO2 around 1.6 μm, the dominating isotope species 12CO2, 13CO2, and 12C18O16O were detected simultaneously without interference by water vapor. Detection limits in the range of few ppmv were obtained for each species utilizing wavelength modulation (WM) spectroscopy with balanced detection in a long-path absorption cell set-up. High sensitivity in conjunction with high precision —typically ±1 per mille and ±6 per mille for 3\% and 0.7\% of CO2, respectively— renders this experimental approach a promising analytical concept for isotope-ratio determination of carbon dioxide in soil and breath gas. For a moderate 12CO2 line, the pressure dependence of the line profile was characterized in detail, to account for pressure effects on sensitive measurements.},
subject = {Isotopenverh{\"a}ltnis},
language = {en}
}
@misc{SchulerLipmanSteinbachetal.2005,
author = {Schuler, Benjamin and Lipman, Everett A. and Steinbach, Peter J. and Kumke, Michael Uwe and Eaton, William A.},
title = {Polyproline and the "spectroscopic ruler" revisited with single-molecule fluorescence},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12229},
year = {2005},
abstract = {To determine whether F{\"o}rster resonance energy transfer (FRET) measurements can provide quantitative distance information in single-molecule fluorescence experiments on polypeptides, we measured FRET efficiency distributions for donor and acceptor dyes attached to the ends of freely diffusing polyproline molecules of various lengths. The observed mean FRET efficiencies agree with those determined from ensemble lifetime measurements but differ considerably from the values expected from F{\"o}rster theory, with polyproline treated as a rigid rod. At donor-acceptor distances much less than the F{\"o}rster radius R0, the observed efficiencies are lower than predicted, whereas at distances comparable to and greater than R0, they are much higher. Two possible contributions to the former are incomplete orientational averaging during the donor lifetime and, because of the large size of the dyes, breakdown of the point-dipole approximation assumed in F{\"o}rster theory. End-to-end distance distributions and correlation times obtained from Langevin molecular dynamics simulations suggest that the differences for the longer polyproline peptides can be explained by chain bending, which considerably shortens the donor-acceptor distances.},
language = {en}
}
@misc{LemkeFernandezTrujilloLoehmannsroeben2005,
author = {Lemke, Matthias and Fern{\´a}ndez-Trujillo, Rebeca and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
title = {In-situ LIF analysis of biological and petroleum-based hydraulic oils on soil},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12268},
year = {2005},
abstract = {Absorption and fluorescence properties of 4 hydraulic oils (3 biological and 1 petroleum-based) were investigated. In-situ LIF (laser-induced fluorescence) analysis of the oils on a brown sandy loam soil was performed. With calibration, quantitative detection was achieved. Estimated limits of detection were below ca. 500 mg/kg for the petroleum-based oil and ca. 2000 mg/kg for one biological oil. A semi-quantitative classification scheme is proposed for monitoring of the biological oils. This approach was applied to investigate the migration of a biological oil in soil-containing compartments, namely a soil column and a soil bed.},
language = {en}
}
@misc{KumkeEidner2005,
author = {Kumke, Michael Uwe and Eidner, Sascha},
title = {Fluorescence and energy transfer processes of humic substances and related model compounds in terbium complexes},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12255},
year = {2005},
abstract = {The fluorescence properties and the fluorescence quenching by Tb3+ of substituted benzoic acid were investigated in solution at different pH. The substituted benzoic acids were used as simple model compounds for chromophores present in humic substances (HS). It is shown that the fluorescence properties of the model compounds resemble fluorescence of HS quite well. A major factor determining the fluorescence of model compounds are proton transfer reactions in the electronically excited state. It is intriguing that the fluorescence of the model compounds was almost not quenched by Tb3+ while the HS fluorescence was decreased very effectively. From our results we concluded that proton transfer reactions as well as conformational reorientation processes play an important role in the fluorescence of HS. The luminescence of bound Tb3+ was sensitized by an energy transfer step upon excitation of the model compounds and of HS, respectively. For HS the observed sensitization was dependent on its origin indicating differences 1) in the connection between chromophores and binding sites and 2) in the energy levels of the chromophore triplet states. Hence, the observed sensitization of the Tb3+ luminescence could be useful to characterize structural differences of HS in solution. Interlanthanide energy transfer between Tb3+ and Nd3+ was used to determine the average distance R between both ions using the well-known formalism of luminescence resonance energy transfer. R was dependent on the origin of the HS reflecting the difference in structure. The value of Rmin seemed to be a unique feature of the HS. It was further found that upon variation of the pH R also changed. This demonstrates that the measurement of interlanthanide energy transfer can be used as a direct method to monitor conformational changes in HS.},
language = {en}
}
@misc{SchmaelzlinDongenKlimantetal.2005,
author = {Schm{\"a}lzlin, Elmar and Dongen, Joost T. van and Klimant, Ingo and Marmod{\´e}e, Bettina and Steup, Martin and Fishahn, Joachim and Geigenberger, Peter and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
title = {An optical multifrequency phase-modulation method using microbeads for measuring intracellular oxygen concentrations in plants},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12232},
year = {2005},
abstract = {A technique has been developed to measure absolute intracellular oxygen concentrations in green plants. Oxygen-sensitive phosphorescent microbeads were injected into the cells and an optical multifrequency phase-modulation technique was used to discriminate the sensor signal from the strong autofluorescence of the plant tissue. The method was established using photosynthesis-competent cells of the giant algae Chara corallina L., and was validated by application to various cell types of other plant species.},
language = {en}
}
@misc{HildebrandtCharbonniereZiesseletal.2006,
author = {Hildebrandt, Nico and Charbonni{\`e}re, Lo{\"i}c J. and Ziessel, Raymond F. and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
title = {Quantum dots as resonance energy transfer acceptors for monitoring biological interactions},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12213},
year = {2006},
abstract = {Quantum dots (QDs) are common as luminescing markers for imaging in biological applications because their optical properties seem to be inert against their surrounding solvent. This, together with broad and strong absorption bands and intense, sharp tuneable luminescence bands, makes them interesting candidates for methods utilizing Forster Resonance Energy Transfer (FRET), e. g. for sensitive homogeneous fluoroimmunoassays (FIA). In this work we demonstrate energy transfer from Eu3+-trisbipyridin (Eu-TBP) donors to CdSe-ZnS-QD acceptors in solutions with and without serum. The QDs are commercially available CdSe-ZnS core-shell particles emitting at 655 nm (QD655). The FRET system was achieved by the binding of the streptavidin conjugated donors with the biotin conjugated acceptors. After excitation of Eu-TBP and as result of the energy transfer, the luminescence of the QD655 acceptors also showed lengthened decay times like the donors. The energy transfer efficiency, as calculated from the decay times of the bound and the unbound components, amounted to 37\%. The Forster-radius, estimated from the absorption and emission bands, was ca. 77{\AA}. The effective binding ratio, which not only depends on the ratio of binding pairs but also on unspecific binding, was obtained from the donor emission dependent on the concentration. As serum promotes unspecific binding, the overall FRET efficiency of the assay was reduced. We conclude that QDs are good substitutes for acceptors in FRET if combined with slow decay donors like Europium. The investigation of the influence of the serum provides guidance towards improving binding properties of QD assays.},
language = {en}
}
@misc{SchmaelzlinWalzKlimantetal.2006,
author = {Schm{\"a}lzlin, Elmar and Walz, Bernd and Klimant, Ingo and Schewe, Bettina and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
title = {Monitoring hormone-induced oxygen consumption in the salivary glands of the blowfly, Calliphora vicina, by use of luminescent microbeads},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12206},
year = {2006},
abstract = {The salivary glands of the blowfly were injected with luminescent oxygen-sensitive microbeads. The changes in oxygen content within individual gland tubules during hormone-induced secretory activity were quantified. The measurements are based on an upgraded phase-modulation technique, where the phase shift of the sensor phosphorescence is determined independently from concentration and background signals. We show that the combination of a lock-in amplifier with a fluorescence microscope results in a convenient setup to measure oxygen concentrations within living animal tissues at the cellular level.},
language = {en}
}
@misc{EngelhardKumkeLoehmannsroeben2006,
author = {Engelhard, Sonja and Kumke, Michael Uwe and L{\"o}hmannsr{\"o}ben, Hans-Gerd},
title = {OPQS - optical process and quality sensing : exemplary applications in the beerbrewing and polyurethane foaming processes},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12191},
year = {2006},
abstract = {Optical methods play an important role in process analytical technologies (PAT). Four examples of optical process and quality sensing (OPQS) are presented, which are based on three important experimental techniques: near-infrared absorption, luminescence quenching, and a novel method, photon density wave (PDW) spectroscopy. These are used to evaluate four process and quality parameters related to beer brewing and polyurethane (PU) foaming processes: the ethanol content and the oxygen (O2) content in beer, the biomass in a bioreactor, and the cellular structures of PU foam produced in a pilot production plant.},
language = {en}
}
@misc{LoehmannsroebenBeckHildebrandtetal.2006,
author = {L{\"o}hmannsr{\"o}ben, Hans-Gerd and Beck, Michael and Hildebrandt, Niko and Schm{\"a}lzlin, Elmar and van Dongen, Joost T.},
title = {New challenges in biophotonics : laser-based fluoroimmuno analysis and in-vivo optical oxygen monitoring},
url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-10120},
year = {2006},
abstract = {Two examples of our biophotonic research utilizing nanoparticles are presented, namely laser-based fluoroimmuno analysis and in-vivo optical oxygen monitoring. Results of the work include significantly enhanced sensitivity of a homogeneous fluorescence immunoassay and markedly improved spatial resolution of oxygen gradients in root nodules of a legume species.},
subject = {Sauerstoff},
language = {en}
}