@misc{BoyadzhievLangenstrassenEvtimovaetal.2007, author = {Boyadzhiev, Marin and Langenstraßen, Rainer and Evtimova, Rozeta and Nenkova, Sanchi and Behrendt, Gerhard}, title = {Development of Branched Aromatic Polyester Polyols from PET}, series = {Wissenschaftliche Beitr{\"a}ge 2007}, volume = {12}, journal = {Wissenschaftliche Beitr{\"a}ge 2007}, issn = {0949-8214}, doi = {10.15771/0949-8214_2007_1_2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus-389}, pages = {11 -- 16}, year = {2007}, abstract = {Diese Arbeit befasst sich mit einer neuen Klasse verzweigter aromatischer Polyesterpolyole (APP), die auf PET-Abf{\"a}llen basieren und f{\"u}r die Herstellung hochwertiger Polyurethane entwickelt wurden. Dieses Ziel wurde durch eine modifizierte Umesterung von PET durch eine Glykolmischung mit einem geringen Anteil Triolen erreicht. Es wurde eine Reihe verzweigter APP mit Hydroxylzahlen im Bereich von 260 bis 380 mg KOH/g und Hydroxyl-Funktionalit{\"a}ten zwischen 2,00 und 2,30 erhalten. Die Viskosit{\"a}t der Produkte steigt im Bereich der Funktionalit{\"a}t von 2,03 bis 2,12 geringf{\"u}gig und dar{\"u}ber st{\"a}rker an. F{\"u}r jede Reihe der APP mit Hydroxylzahlen von 260, 320 bzw. 380 mg KOH/g wurde bez{\"u}glich der Viskosit{\"a}t, der Langzeitstabilit{\"a}t und der Hydroxyl-Funktionalit{\"a}t ein Eigenschaftsoptimum gefunden. APP mit h{\"o}herer Hydroxyl-Funktionalit{\"a}t k{\"o}nnen zur Herstellung von Polyurethan-Gießharzen und jene mit niedrigeren Hydroxylzahlen f{\"u}r Beschichtungen, z. B. von Leder, verwendet werden.}, language = {en} } @misc{PeshkovEvtimovaHerzogetal.2011, author = {Peshkov, Vladimir and Evtimova, Rozeta and Herzog, Michael and Behrendt, Gerhard}, title = {New Synthesis Route for PHD Polyols}, series = {Wissenschaftliche Beitr{\"a}ge 2011}, volume = {15}, journal = {Wissenschaftliche Beitr{\"a}ge 2011}, issn = {0949-8214}, doi = {10.15771/0949-8214_2011_1_9}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus-1105}, pages = {67 -- 72}, year = {2011}, abstract = {The synthesis of polyurea dispersion polyols (PHD) was developed using a new route via depolymerization of polyurethane polyureas by a mixture of at least two glycols in the presence of a consumable catalyst, i. e. a secondary aliphatic amine. On this way such polyols were produced with a particle size distribution with a maximum in the 120 to 400 nanometer region with hydroxyl numbers of 180 to 300 mg KOH/g being optically clear and highly reactive. The exact adjustment of the ethylene oxide content of the reaction mixture together with that of the polyether polyol originally present in the polyurethane polyurea used in a predetermined range of surface tension as well as specific reaction conditions leads to these polyols which will give in turn polyurethanes with exceptional properties.}, language = {en} } @misc{RichterChenKoegleretal.2011, author = {Richter, Asta and Chen, Chun-Liang and K{\"o}gler, Reinhard and Talut, Georg}, title = {Irradiation effects in nanostructured FeCrAl oxide dispersion strengthened steel}, series = {Wissenschaftliche Beitr{\"a}ge 2011}, volume = {15}, journal = {Wissenschaftliche Beitr{\"a}ge 2011}, issn = {0949-8214}, doi = {10.15771/0949-8214_2011_1_10}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus-1112}, pages = {73 -- 79}, year = {2011}, abstract = {Nanostructured ferritic oxide dispersion strengthened (ODS) alloy is an ideal candidate for fission/fusion power plant materials, particularly in the use of a first-wall and blanket structure of a next generation reactor. These steels usually contain a high density of Y-Al-O nanoparticles, high dislocation densities and fine grains. The material contains nanoparticles with an average diameter of 21 nm. Irradiation of these alloys was performed with a dual beam irradiation of 2.5 MeV Fe+/31 dpa and 350 keV He+/18 appm/dpa. Irradiation causes atomic displacements resulting in vacancy and self-interstitial lattice defects and dislocation loops. Additionally to structural changes, the effect of the irradiation generated defects on the mechanical properties of the ODS is investigated by nanoindentation. A clear hardness increase in the irradiated area is observed, which reaches a maximum at a close surface region. This feature is attributed to synergistic effects between the displacement damage and He implantation resulting in He filled vacancies}, language = {en} } @article{GoebelDietzLisdat2009, author = {G{\"o}bel, Gero and Dietz, T. and Lisdat, Fred}, title = {Biosensor based on an oxygen reducing bilirubin oxidase electrode}, series = {Procedia Chemistry}, volume = {1}, journal = {Procedia Chemistry}, number = {1}, issn = {1876-6196}, doi = {10.1016/j.proche.2009.07.068}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-6237}, pages = {273 -- 276}, year = {2009}, abstract = {An oxygen reducing electrode made of bilirubin oxidase and multi-walled carbon nanotubes (BOD-MWCNT-Au electrode) is coupled to enzymes catalysing oxygen-consuming reactions such as glucose oxidase (GOD) to result in a membrane-free bienzyme electrode. The feasibility of such a molecularly assembled system stabilized by covalent linkage has been demonstrated. The electrochemical characterisation of the bienzyme electrode reveals sensitivity to the enzyme substrate. The results indicate that the BOD-electrode provides a suitable platform for sensing analytes for which oxidases of high activity are available.}, language = {en} } @article{FeifelStiegerKappetal.2016, author = {Feifel, Sven Christian and Stieger, Kai Ralf and Kapp, Andreas and Weber, Dennis and Allegrozzi, Marco and Piccioli, Mario and Turano, Paola and Lisdat, Fred}, title = {Insights into Interprotein Electron Transfer of Human Cytochrome c Variants Arranged in Multilayer Architectures by Means of an Artificial Silica Nanoparticle Matrix}, series = {ACS Omega}, volume = {1}, journal = {ACS Omega}, number = {6}, issn = {2470-1343}, doi = {10.1021/acsomega.6b00213}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-6753}, pages = {1058 -- 1066}, year = {2016}, abstract = {The redox behavior of proteins plays a crucial part in the design of bioelectronic systems. We have demonstrated several functional systems exploiting the electron exchange properties of the redox protein cytochrome c (cyt c) in combination with enzymes and photoactive proteins. The operation is based on an effective reaction at modified electrodes but also to a large extent on the capability of self-exchange between cyt c molecules in a surface-fixed state. In this context, different variants of human cyt c have been examined here with respect to an altered heterogeneous electron transfer (ET) rate in a monolayer on electrodes as well as an enhanced self-exchange rate while being incorporated in multilayer architectures. For this purpose, mutants of the wild-type (WT) protein have been prepared to change the chemical nature of the surface contact area near the heme edge. The structural integrity of the variants has been verified by NMR and UV-vis measurements. It is shown that the single-point mutations can significantly influence the heterogeneous ET rate at thiol-modified gold electrodes and that electroactive protein/silica nanoparticle multilayers can be constructed with all forms of human cyt c prepared. The kinetic behavior of electron exchange for the mutant proteins in comparison with that of the WT has been found altered in some multilayer arrangements. Higher self-exchange rates have been found for K79A. The results demonstrate that the position of the introduced change in the charge situation of cyt c has a profound influence on the exchange behavior. In addition, the behavior of the cyt c variants in assembled multilayers is found to be rather similar to the situation of cyt c self-exchange in solution verified by NMR.}, language = {en} } @article{WegerichTuranoAllegrozzietal.2009, author = {Wegerich, F. and Turano, Paola and Allegrozzi, Marco and M{\"o}hwald, H. and Lisdat, Fred}, title = {Superoxide Biosensing with Engineered Cytochrome c}, series = {Procedia Chemistry}, volume = {1}, journal = {Procedia Chemistry}, number = {1}, issn = {1876-6196}, doi = {10.1016/j.proche.2009.07.321}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-6523}, pages = {1287 -- 1290}, year = {2009}, abstract = {Several mutation positions have been chosen for introducing positively charged lysines in human cytochrome c (cyt c) with the aim of increasing the reaction rate with superoxide radicals (SO) and thus, the sensitivity of an electrochemical cyt c based SO biosensor. The impact of the mutations on structural and redox properties as well as on the reaction rate with SO are verified. Four mutants show a higher reaction rate with the radical compared to the wild type. These mutants are used for the construction of SO sensors based on thiol-modified gold electrodes and covalently fixed proteins. The E66K mutant electrode has a clearly higher sensitivity in comparison to the wildtype based sensor.}, language = {en} } @misc{AlowGerassimowaKorikowetal.2001, author = {Alow, Jewgeni M. and Gerassimowa, Nina P. and Korikow, Pjotr W. and Moskwitschjow, Juri A. and Noshnin, Nikolai A. and Paschinin, Alexej N.}, title = {Synthese neuer organischer Schwefelverbindungen aus aromatischen Thiolverbindungen und Sulphins{\"a}uren}, series = {Wissenschaftliche Beitr{\"a}ge 2001}, volume = {6}, journal = {Wissenschaftliche Beitr{\"a}ge 2001}, issn = {0949-8214}, doi = {10.15771/0949-8214_2001_2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-8318}, pages = {11 -- 15}, year = {2001}, abstract = {Die rasche Entwicklung der Chemie organischer Schwefelverbindungen in der zweiten H{\"a}lfte des 20. Jahrhunderts wurde durch drei wichtige Prozesse ausgel{\"o}st: - die Einbeziehung von schwefelhaltigen und stark schwefelhaltigen Erd{\"o}len sowie die Verwendung von schwefelhaltigen Abf{\"a}llen zur Steigerung der Produktion, die durch die Entwicklung anderer Industriebranchen notwendig wurde; - die Erweiterung der Anwendungsbereiche von organischen Schwefelverbindungen bei der Produktion von Arzneimitteln, Pestiziden, Flotationsmitteln, Zusatzstoffen f{\"u}r {\"O}le und Heizstoffe, Inhibitoren gegen Metallkorrosion, Polymerisationsreglern, Farbstoffen u. a.; - durch das große Interesse an organischen Schwefelverbindungen als Modelle f{\"u}r die Erforschung vieler wichtiger Grundlagenkonzeptionen in der organischen Chemie. Aus diesem Grunde ist die Synthese neuer organischer Schwefelverbindungen mit potenziell n{\"u}tzlichen Eigenschaften sowie die Untersuchung der Gesetzm{\"a}ßigkeiten des Reaktionsverlaufs mit dem Ziel, diese Prozesse bewusst zu steuern, von besonderer Aktualit{\"a}t. In der vorliegenden Arbeit wurden Reaktionen der nukleophilen Addition von aromatischen Thiolverbindungen und Sulfins{\"a}uren an aktivierte Doppelbindungen (Vinylketone und Akrylnitrile) und die weitere Umwandlung der entstandenen Addukte zu heterozyklischen Verbindungen untersucht.}, language = {de} } @misc{KochStuhrNaber2006, author = {Koch, Hagen and Stuhr, Wolfgang and Naber, Bernhard W.}, title = {PUR-Kaltformweichschaumstoff: eine interessante Rohstoffquelle f{\"u}r neue Polyurethansynthesen}, series = {Wissenschaftliche Beitr{\"a}ge 2006}, volume = {11}, journal = {Wissenschaftliche Beitr{\"a}ge 2006}, issn = {0949-8214}, doi = {10.15771/0949-8214_2006_1_9}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus-278}, pages = {51 -- 54}, year = {2006}, abstract = {Es wurde ein chemisches Recyclingverfahren f{\"u}r PUR entwickelt, welches durch Einsatz eines Extruders und in Tandemfahrweise betriebener Nachreaktionsbeh{\"a}lter kontinuierlich gestaltet wurde. In Nebenreaktionen entstandene prim{\"a}re aromatische Amine werden in einer synchron zur Hauptreaktion verlaufenden Umsetzung in stickstoffhaltige Polyole umgewandelt. Die chemischen und anwendungstechnischen Eigenschaften der nach diesem Verfahren hergestellten Recyclatpolyole werden dargestellt. Diese Polyole sind zur Formulierung harter, halbharter und z{\"a}hharter zelliger und nichtzelliger PUR geeignet. Die Betrachtung {\"o}konomischer und {\"o}kologischer Gesichtspunkte schließt die Arbeit ab.}, language = {de} } @misc{LangenstrassenFulevApeletal.2006, author = {Langenstraßen, Rainer and Fulev, Stanislav and Apel, Andreas and Gebert, Bodo and Lehmann, Dieter}, title = {Entwicklung einer Anlage zur kontinuierlichen Herstellung von PET-Recyclingpolyolen}, series = {Wissenschaftliche Beitr{\"a}ge 2006}, volume = {11}, journal = {Wissenschaftliche Beitr{\"a}ge 2006}, issn = {0949-8214}, doi = {10.15771/0949-8214_2006_1_10}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus-284}, pages = {55 -- 64}, year = {2006}, abstract = {Diese Arbeit hat die Entwicklung einer Anlage zum Ziel, mit der aus festem Polyethylenterephthalat (PET), wie es als Produktionsabfall bei seiner Herstellung und Verarbeitung entsteht, durch Umesterungen in Gegenwart von Glykolen und/oder oligomeren Estern Aromatische Polyesterpolyole (APP) als Rohstoffe f{\"u}r Polyurethane kontinuierlich hergestellt werden k{\"o}nnen. Die Arbeit baut auf den bisherigen Entwicklungen zur diskontinuierlichen Herstellung von Recyclingpolyolen aus PET-Abf{\"a}llen an der Technischen Fachhochschule Wildau auf. Mit Hilfe dieses Verfahrens k{\"o}nnen Polyesterpolyole verschiedener Eigenschaften f{\"u}r unterschiedliche Einsatzgebiete, z. B. Polyurethan-Hartschaumstoffe, -Beschichtungen, -Vergussmassen etc., hergestellt werden, die nur durch Modifizierungen in der Menge der Ausgangsstoffe und der Verfahrensbedingungen an die Erfordernisse angepasst werden. Dieses Verfahren liefert im diskontinuierlichen Betrieb qualitativ hochwertige Polyesteralkohole in einem breiten Parameterbereich. Auf Grund des hohen Aromatenanteils besitzen sie einen inh{\"a}renten Flammschutz. {\"U}ber Grundlagenuntersuchungen zum L{\"o}sevorgang von PET in verschiedenen L{\"o}sungsmitteln unter thermischer und mechanischer Beanspruchung und zur Umesterung der PET-L{\"o}sung zu oligomeren Produkten unter diskontinuierlichen Laborbedingungen, die auf einer Miniplantanlage ausgef{\"u}hrt wurden, ist bereits berichtet worden. Aufbauend auf diesen Ergebnissen soll eine kontinuierlich arbeitende Anlage konstruiert und gebaut werden, die zur Bestimmung der Verfahrensparameter der kontinuierlichen Glykolyse von PET dient. Die in dieser Arbeit ermittelten verfahrenstechnischen und konstruktiven Grundlagen stellen die Basis zur Maßstabsvergr{\"o}ßerung f{\"u}r die Konstruktion und den Bau gr{\"o}ßerer Anlagen, einer Technikums- und darauf aufbauend einer Pilotanlage, dar. F{\"u}r ein kontinuierliches Verfahren zur Herstellung von Polyesterpolyolen aus PET gibt es weltweit kein Beispiel und auch keine gesch{\"u}tzte L{\"o}sung, so dass mit dieser Arbeit wissenschaftliches und technisches Neuland betreten wird. Das rohstoffliche Recycling der PET-Abf{\"a}lle ist bisher nur diskontinuierlich durchgef{\"u}hrt worden. Das diskontinuierliche Verfahren hat jedoch eine Reihe von Nachteilen, die vor allem in der langen L{\"o}sephase f{\"u}r das PET im Glykolyse-Gemisch, in l{\"a}ngeren Reaktionszeiten, in den schwankenden Parametern der Produkte sowie in der zu geringen Wirtschaftlichkeit begr{\"u}ndet liegen. Ein kontinuierliches Verfahren h{\"a}tte demgegen{\"u}ber die Vorteile einer konstanten Produktqualit{\"a}t und einer verbesserten Wirtschaftlichkeit. Nach eigenen Kostenabsch{\"a}tzungen gewinnt ein kontinuierliches Verfahren bei einem Durchsatz von mehr als etwa 1000 t/a an Wirtschaftlichkeit gegen{\"u}ber einer diskontinuierlichen Verfahrensweise, da dann die Vorteile des kontinuierlichen Verfahrens (geringere Personalkosten, gleichbleibende Produktqualit{\"a}t) die Nachteile (h{\"o}here Investitionskosten, h{\"o}herer Energiebedarf) {\"u}berwiegen.}, language = {de} } @article{RangelovaRadevNenkovaetal.2011, author = {Rangelova, Nadezhda and Radev, Lachezar and Nenkova, Sanchi and Salvado, Isabel Miranda and Vas Fernandes, Maria and Herzog, Michael}, title = {Methylcellulose/SiO2 hybrids: sol-gel preparation and characterization by XRD, FTIR and AFM}, series = {Central European Journal of Chemistry}, volume = {9}, journal = {Central European Journal of Chemistry}, number = {1}, issn = {2391-5420}, doi = {10.2478/s11532-010-0123-y}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-9636}, pages = {112 -- 118}, year = {2011}, abstract = {Methylcellulose (MC) / SiO2 organic / inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO2. AFM depicts surface roughness which depends on the silica precursor and MC content.}, language = {en} } @article{DimitrovHerzogNenkova2013, author = {Dimitrov, Kiril and Herzog, Michael and Nenkova, Sanchi}, title = {Fe3O4 Modification of Microcrystalline Cellulose for Composite Materials}, series = {American Journal of Chemistry}, volume = {3}, journal = {American Journal of Chemistry}, number = {5}, issn = {2165-8781}, doi = {10.5923/j.chemistry.20130305.04}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-9651}, pages = {140 -- 147}, year = {2013}, abstract = {A new synthesis method for producing cellulose ferrite micro- and nano- composites was developed and new material properties were studied. Microcrystalline cellulose was modified with a mixture of Fe+2/Fe+3 to produce surface bonded nanoparticles magnetite (Fe3O4). Optimal conditions were determined. Microsized hematite (Fe2O3) was mixed with microcrystalline cellulose and used as a reference. The magnetite modified microcrystalline cellulose and hematite filled microcrystalline cellulose were used together with polyurethane prepolymer. New composite crosslinked conductivity materials based on the magnetite modified microcrystalline or hematite filled microcrystalline cellulose and polyurethane were developed. Morphology, crystalline properties, water absorption and electro conductivity of these materials were characterized. The physical properties of these materials were characterized by different analytical methods: SEM, XRD, water absorption and electrical resistance.}, language = {en} } @article{TsonevHerzogNenkova2013, author = {Tsonev, Tsvetomir and Herzog, Michael and Nenkova, Sanchi}, title = {Shape memory polyurethanes based on recycled polyvinyl butyral. I. Synthesis and morphology}, series = {Central European Journal of Chemistry}, volume = {11}, journal = {Central European Journal of Chemistry}, number = {12}, issn = {2391-5420}, doi = {10.2478/s11532-013-0331-3}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-9664}, pages = {2058 -- 2065}, year = {2013}, abstract = {Shape memory polyurethanes (SMPUs) were synthesized by 4,4′-diphenylmethane diisocyanate (MDI), hexane-1,6-diol (HD), polypropylene glycol (PPG), and recycled polyvinyl butyral (PVB). Dynamic mechanical analysis, differential scanning calorimetry and Fourier transformation infrared attenuated total reflection spectroscopy was used to characterize the poly (vinylbutyral-urethanes). Micro-phase domain separation of hard and soft segments and phase inversion were investigated. Increasing the hard segment content, i.e., average hard segment molecular weight, leads to an increase in the degree of micro-phase separation, hard domain order and crystallinity. The crystalline hard segment structures combined with the elastic nature of soft segment matrix provide enough physical and chemical crosslinks to have shape memory effect.}, language = {en} } @article{LobsteinZinnMinierietal.2018, author = {Lobstein, Susanne and Zinn, Steffen and Minieri, Marilena and Foitzik, Andreas}, title = {Sample Analysis for Novel Medical Applications}, series = {Materials Science Forum}, volume = {941}, journal = {Materials Science Forum}, publisher = {Trans Tech Publications}, issn = {0255-5476}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-18749}, pages = {2518 -- 2521}, year = {2018}, abstract = {The sample preparation for biological and chemical probes involves following a strict workflow to eliminate any contamination to the sample beforehand. Furthermore, it is time consuming and must be carried out by trained personnel such as a nurse or other supervisors, making it therefore expensive. The development of novel sample preparation techniques paired with modern sample analysis systems is focused on improving the operability while keeping a constant quality of results. This is important to analyse samples, which cannot be determined with current screening conditions. The analysis of analytes is required to receive a more detailed picture of the patient and to fully understand its complexity. Possible samples for in-depth analysis of chemical origin can be cholesterol or glucose. More complex samples, such as blood or saliva, require a sophisticated system, which analyses the samples for their individual compounds.}, language = {en} } @misc{BelkeEvtimovaLangenstrassenetal.2004, author = {Belke, Martin and Evtimova, Rozeta and Langenstraßen, Rainer and Pniok, Iris and Peshkov, Vladimir and Behrendt, Gerhard}, title = {Closed Loop of Polyurethane Flexible Slabstock Foam Wastes by a Chemical Process}, series = {Wissenschaftliche Beitr{\"a}ge 2004}, volume = {9}, journal = {Wissenschaftliche Beitr{\"a}ge 2004}, issn = {0949-8214}, doi = {10.15771/0949-8214_2004_1_1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-3955}, pages = {5 -- 11}, year = {2004}, abstract = {Presently, about 8 million metric tons of polyurethanes are produced in the world annually. During production of precursors, semi-finished products and final products about 5 to 10 \% of this amount is waste, i. e. an amount of about half a million tons. To this add the products after their life cycle. This is a large source of material which should not be given to landfills or incinerators but be used as secondary materials for the production of new polyurethanes.}, language = {en} } @inproceedings{TolkiehnRabeWerner1981, author = {Tolkiehn, G{\"u}nter-Ulrich and Rabe, P. and Werner, A.}, title = {Structure investigation on the hexacyanoferrate-(II) and -(III) complexes}, series = {EXAFS for inorganic systems : Proceedings of the Daresbury Study Weekend March 1981}, booktitle = {EXAFS for inorganic systems : Proceedings of the Daresbury Study Weekend March 1981}, editor = {Garner, C.D. and Hasnain, S.S.}, publisher = {Science and Engineering Research Council}, address = {Daresbury, England}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-7218}, pages = {130 -- 132}, year = {1981}, abstract = {The contribution reports a structure investigation on the hexacyanoferrate-(II) and (III) complexes in solid state and in aqueous solution using EXAFS. Results are discussed and compared with other published data.}, language = {en} }