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101.
S Drescher G Hempel WH Binder B Dobner A Blume A Meister 《Langmuir : the ACS journal of surfaces and colloids》2012,28(31):11615-11624
In the present work, we describe the successful stabilization of bolalipid nanofibers by sol-gel condensation (silicification) of tetraethoxysilane (TEOS) or 3-mercaptopropyltriethoxysilane (MP-TEOS), respectively, onto the nanofibers. The conditions for an effective and reproducible silicification reaction were determined, and the silicification process was pursued by transmission electron microscopy (TEM). The resulting bolalipid-silica composite nanofibers were characterized by means of differential scanning calorimetry (DSC), TEM, (13)C, and (31)P NMR spectroscopy. Finally, the novel silicified bolalipid nanofibers were used as templates for the fixation of 5 and 2 nm AuNPs, respectively, resulting in one of the rare examples of one-dimensional AuNP arrangements in aqueous suspension. 相似文献
102.
M. Hempel J.W. Tomm V. Hortelano N. Michel J. Jim M. Krakowski T. Elsaesser 《Laser \u0026amp; Photonics Reviews》2012,6(6):L15-L19
The propagation of defect networks in failed 980 nm emitting high‐power diode lasers is analyzed. This is accomplished ex post facto by electron‐beam based techniques applied without device preparation and in situ by thermographic microscopy with 1 µs time resolution. Moreover, an iterative model is established, which allows for describing both the shape of the observed defect networks as well as the kinetics of their spread. This concerted approach allows the clear assignment of starting points of extended defect systems as well as analysis of their evolution kinetics. Eventually this knowledge may help in making devices more resistive against defect creation and extension. 相似文献
103.
Olaf Elsholz Carsten Frank Birgit Matyschok Frank Steiner Oliver Wurl Burkhard Stachel Heinrich Reincke Manfred Schulze Ralf Ebinghaus Maximilian Hempel 《Analytical and bioanalytical chemistry》2000,366(2):196-199
A monitor is described which provides the on-line determination of mercury in river water at concentrations from 20 to 1000 ng/L. The measurement includes an on-line digestion with Br–/BrO3 – and UV-radiation. Each determination is controlled by an on-line addition of 50 and 100 ng/L mercury carried out by pre-dilution of a 500 and 1000 ng/L stock solution using sequential injection analysis (SIA). One cycle of analysis takes 20 min and results in nine signals. A five days stand-alone operation has been performed successfully. Details are also published at web page: “http/www.rzbd.fh-hamburg.de/¶~prmercol” 相似文献
104.
Andrew Hempel Norman Camerman Donald Mastropaolo Arthur Camerman 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):1048-1049
In the title compound, dimethyl({5‐[2‐(1‐methylamino‐2‐nitroethenylamino)ethylthiomethyl]‐2‐furyl}methyl)ammonium chloride, C13H23N4O3S+·Cl?, protonation occurs at the dimethylamino N atom. The ranitidine molecule adopts an eclipsed conformation. Bond lengths indicate extensive electron delocalization in the N,N′‐dimethyl‐2‐nitro‐1,1‐ethenediamine system of the molecule. The nitro and methylamino groups are trans across the side chain C=C double bond, while the ethylamino and nitro groups are cis. The Cl? ions link molecules through hydrogen bonds. 相似文献
105.
Andrew Hempel Norman Camerman Donald Mastropaolo Arthur Camerman 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):1225-1227
The crystal structure of the title compound contains four 2,4‐diamino‐5‐methyl‐6‐[(3,4,5‐trimethoxyanilino)methyl]quinazoline molecules, two dimethyl sulfoxide molecules and three water molecules in the asymmetric unit, i.e. 4C19H23N5O3·2C2H6OS·3H2O. All four quinazoline molecules adopt trans,gauche conformations. An extensive hydrogen‐bond network involving N?N base‐pairing interactions, as well as the dimethyl sulfoxide and water molecules, stabilizes the crystal structure. 相似文献
106.
It is an aim of the present work to determine the chemical heat flow rate of a reaction without explicitly solving the heat balance equations. Therefore, it is necessary to calculate the heat flow rate directly from the temperature course of an experimentally determined reaction. For this transformation the transfer function of the calorimeter is needed 1 . An isoperibol reaction calorimeter was used for the experiments. With different calibrations and gained transfer functions, it is shown that the chemical heat flow rate can be determined from the temperature course of a reaction. The evaluation is fast and easy to use, which improves automation and prevents possible input errors. 相似文献
107.
Silke Biedasek Mohammed Abboud Hans-Ulrich Moritz Achim Stammer 《Macromolecular Symposia》2007,259(1):390-396
Summary: Aqueous solutions of acrylic acid were levitated in a 40 kHz acoustic levitator. The monomer amount in the levitated droplets was monitored by Raman spectroscopy relating to an internal standard. Thus evaporation of the monomer as well as polymerization reactions initiated by a redox system were investigated by Raman spectroscopy and resultant data were compared to HPLC data. Decreases in monomer amount due to evaporation can be clearly distinguished from polymerization reactions. Additionally, temperature measurement within the droplet throughout a polymerization reaction shows the typical temperature course originating from the heat of polymerization. 相似文献
108.
Christoph Blaszk Jan Grünitz Maike Möller Werner Pauer Hans-Ulrich Moritz Christian Schwede 《Macromolecular Symposia》2007,259(1):348-353
Summary: Since copolymerization parameters of acrylic acid (AA) and 2-hydroxypropyl acrylate (HPA) in aqueous solutions are scarcely investigated a new method and different experimental setups were developed to run copolymerization experiments at different temperatures and pH values. The experiments were done with UV- or azo- initiation and analyzed by residual monomer analytics with HPLC and GPC methods. Based on the data obtained the conversion and copolymerization parameters were calculated with different mathematical models. 相似文献
109.
Dana Rüttgers Iuliana Negoita Werner Pauer Hans-Ulrich Moritz 《Macromolecular Symposia》2007,259(1):26-31
Summary: Process intensification is investigated by the emulsion polymerization of styrene in the continuous Taylor reactor. The result is an increase in space time yield up to a factor 200 in comparison to a semi-batch polymerization process. This is obtained by a fast emulsion polymerization with a mean residence time, which is reduced to 60 seconds. The article presented the results of the process and the economical aspects of the Taylor reactor plant. 相似文献
110.