Search

Mittels Niederdruckimpaktion wurden durch Spruhtrocknung hergestellte porose Ausgangspartikeln, sogenannte Building Blocks, zu einer porosen Schicht auf einem Substrat aufgebaut. Die Wachstumsrate der Schicht hangt von der Impaktionszeit und vom Kammerdruck ab. Die Porositat der Schichten lasst sich uber den Impaktionsdruck kontrollieren. Die in diesem Experiment gewonnenen Erkenntnisse konnen fur das Aufbringen von dreidimensionalen porosen Schichten mit einstellbarer Porengrosenverteilung auf beliebigen Substraten verwendet werden. Porous films of spray dried nanoparticles, so-called building blocks, were prepared using low pressure impaction. The growth rate of the films depends on the impaction time and impaction pressure. The porosity of the films can be controlled via the impaction pressure. This method can be used for the preparation of three-dimensional porous layers with tunable pore size distribution on an arbitrary substrate.

Porose Partikeln mit definierten Porenstrukturen sind fur Anwendungen im Bereich der Katalysatoren von Interesse. Kugelformige SiO2‐Agglomerate mit einstellbaren Porengrosen wurden durch einen einfachen aerosolbasierten Prozess hergestellt. Weiterhin bietet diese Methode die Moglichkeit zur kontinuierlichen Synthese von Nanokompositpartikeln.

A series of meso-ester-substituted BODIPY deriva- tives 1-6 are synthesized and characterized. In particular, dyes functionalized with oligo(ethylene glycol) ether styryl or naphthalene vinylene groups at the a positions of the BODIPY core (3-6) become partially soluble in water, and their absorptions and emissions are located in the far-red or near-infrared region. Three synthetic approaches are at- tempted to access the meso-carboxylic acid (COOH)-substi- tuted BODIPYs 7 and 8 from the meso-ester-substituted BODIPYs. Two feasible synthetic routes are developed suc- cessfully, including one short route with only three steps. The meso-COOH-substituted BODIPY 7 is completely soluble in pure water, and its fluorescence maximum reaches around 650 nm with a fluorescence quantum yield of up to 15 %. Time-dependent density functional theory calculations are conducted to understand the structure-optical proper- ties relationship, and it is revealed that the Stokes shift is de- pendent mainly on the geometric change from the ground state to the first excited singlet state. Furthermore, cell stain- ing tests demonstrate that the meso-ester-substituted BODIPYs (1 and 3-6) and one of the meso-COOH-substituted BODIPYs (8) are very membrane-permeable. These features make these meso-ester- and meso-COOH-substituted BODIPY dyes attractive for bioimaging and biolabeling applications in living cells.

Der Transportmechanismus von mittels Platin-Katalysator aktiviertem Sauerstoff wurde mit einem System aus Nanopartikeln-Schichten (Sandwichstruktur) untersucht. Die Ergebnisse zeigen, dass die aktivierte Sauerstoffspezies uber die Gasphase transportiert wird, und dass der bisher allgemein akzeptierte Oberflachentransport (Spillover) vernachlassigbar ist. Allerdings ist die Lebensdauer der aktivierten Sauerstoffspezies sehr begrenzt. Aus Versuchen mit raumlich getrennten Pt- und C-Schichten wurde die Lebensdauer auf 65 ms abgeschatzt. Der Abbau der aktivierten Sauerstoffspezies erfolgt vermutlich uber die Anlagerung an andere Gasmolekule oder an Wande. Die Identifizierung des dominanten Transportmechanismus und Quantifizierung der katalytischen Wirkung konnte wertvolle Hinweise fur die Optimierung des Designs von katalytisch beschichteten Dieselruspartikelfiltern geben. The transport mechanism of oxygen activated on platinum catalysts was investigated with a system of nanoparticle layers (sandwich structure). The results indicate that activated oxygen is transported via the gas phase and that the generally accepted surface transport, so-called spillover, is negligible. However, the lifetime of the activated oxygen is very limited. In experiments with spatially separated Pt- and C-layers the lifetime was estimated to be 65 ms. The reduction of activated oxygen presumably occurs via attachment to other gas molecules or to reactor walls. The identification of the dominant transport mechanism and the quantification of the catalytic effect could provide valuable guidelines for the design optimization of catalytic coated diesel particulate filters.

Die katalytische Oxidation von Kohlenstoffpartikeln ist u. a. bei der Regenerierung von Dieselrus-Partikelfiltern von Bedeutung. Besteht zwischen Katalysator und Kohlenstoffpartikeln kein direkter Kontakt, so ist ein Transportschritt der aktivierten Sauerstoffatome notwendig (Oxygen-Spillover). Die Reichweite der aktivierten Sauerstoffatome an Nanopartikel-Schichtsystemen wurde untersucht. Die Partikelschichten bestanden aus einer ca. 20 μm dicken Platin-Katalysatorschicht und einer ca. 300 μm dicken Kohlenstoffschicht, die durch eine inerte SiO2-Partikelschicht mit variabler Dicke getrennt waren. Bei moderaten Umsatzen (&n60; 40 %), die noch ohne substantielle Anderungen der Struktur der C-Partikelschicht ablaufen, wurde eine Reichweite von ca. 160 μm gefunden. Die Reichweite der oxidierenden Spezies kann einen Ausgangspunkt bei der geometrischen Gestaltung von effizienteren katalytisch impragnierten Ruspartikelfiltern bilden. The catalytic oxidation of carbon particles is an important process, e.g., in regeneration of diesel particulate filters. If the catalyst and the carbon particles are not in direct contact, a transportation step of the activated oxygen atoms (oxygen spillover) is needed. The distance of oxygen spillover in a nanoparticle layer system was studied. The system consisted of a platinum catalyst (20 μm thick) and a carbon (300 μm thick) layer that were separated by an inert SiO2 layer with variable thickness. At moderate conversion (&n60; 40 %), which occurs without substantial structural changes of the carbon particle layer, a distance of 160 μm was found. The spillover distance of the oxidizing species may be a starting point for the geometric design of more efficient impregnated catalytic particulate filters.

The chitosan was degraded by the cheap, efficient, and commercially available enzymes in hydrochloric acid solution. The effect of molar ratio of added HCl to NH2 of chitosan on the degradation was investigated, and the favorable ratio was between 0.50 and 0.95. The chitooligomer hydrochlorides were directly prepared by this simple method. The chitooligomer hydrochlorides were characterized by thermogravimetric analysis, differential thermal analysis, and Fourier transform infrared. These results show that the obtained chitooligomer hydrochlorides were much more stable than the chitooligomer acetates. This preparation procedure of chitooligomer hydrochlorides was simple and cheap, and helpful for the preservation of chitooligomers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Chitosan-N-2-hydroxypropyl trimethyl ammonium chloride (QTS) was prepared by reaction of chitosan with glycidyl trimethylammonium chloride, which was characterized by FTIR. QTS with different molecular weights (Mw 41.55 × 104, 9.02 × 104, 3.57 × 104, and 0.17 × 104) showed biocidal activity on Staphylococcua aureus, Bacillus subtilis, Staphylococcua epidermidis, and Candida albicans. QTS with high molecular weight had high biocidal activity on the gram-positive bacteria, and the biocidal effect of QTS decreased with decreasing molecular weight from 9.02 × 104 to 0.17 × 104. QTS with Mw 41.55 × 104 exhibits slightly lower biocidal activity on Candida albicans than other QTS samples. However, no remarkable biocidal activity of QTS was found on gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa at the concentration up to 10 g L−1. Existence of cationic surfactant, amphoteric surfactant, nonionic surfactant, Ca2+ and Mg2+ had no remarkable effect on microbiocidal activity of these QTS samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3851–3856, 2007