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981.
The Fmoc protection group is among the most commonly used protection groups for the amino function. A fast method for the thermal deavage of this protection group under base-free conditions without the need for dibenzofulvene scavengers is presented. The advantages of this method include straightforward testability by means of a simple high-temperature NMR experiment, usually high yields, and good selectivity towards the BOC protection group and t-butyl ethers. 相似文献
982.
Smrati Gupta Mukesh Agrawal Marc Conrad Naima Aurelia Hutter Phillip Olk Frank Simon Lukas M. Eng Manfred Stamm Rainer Jordan 《Advanced functional materials》2010,20(11):1756-1761
A simple, fast, and versatile approach to the fabrication of outstanding surface enhanced Raman spectroscopy (SERS) substrates by exploiting the optical properties of the Ag nanoparticles and functional as well as organizational characteristics of the polymer brushes is reported. First, poly(2‐(dimethylamino)ethyl methacrylate) brushes are synthesized directly on glassy carbon by self‐initiated photografting and photopolymerization and thoroughly characterized in terms of their thickness, wettability, morphology, and chemical structure by means of ellipsometry, contact angle, AFM, and XPS, respectively. Second, Ag nanoparticles are homogeneously immobilized into the brush layer, resulting in a sensor platform for the detection of organic molecules by SERS. The surface enhancement factor (SEF) as determined by the detection of Rhodamine 6G is calculated as 6 × 106. 相似文献
983.
Peterhoff D Zellner H Guldan H Merkl R Sterner R Babinger P 《Chembiochem : a European journal of chemical biology》2012,13(9):1297-1303
We have identified the native dimer interface of heptaprenylglyceryl phosphate synthase PcrB from the bacterium Bacillus subtilis and analyzed the significance of oligomer formation for stability and catalytic activity. Computational methods predicted two different surface regions of the PcrB protomer that could be responsible for dimer formation. These bona fide interfaces were assessed both in silico and experimentally by the introduction of amino acid substitutions that led to monomerization, and by incorporation of an unnatural amino acid to allow cross-linking of the two protomers. The results showed that, in contrast to previous assumptions, PcrB uses the same interface for dimerization as the homologous geranylgeranylglyceryl phosphate synthase from Archaea. Thermal unfolding demonstrated that the monomeric proteins are only slightly less stable than wild-type PcrB. However, activity assays showed that monomerization limits the length of accepted polyprenyl pyrophosphates to three isoprene units, whereas the native PcrB substrate contains seven isoprene entities. We provide a plausible hypothesis as to how dimerization determines substrate specificity of PcrB. 相似文献
984.
985.
Birgit Finke Martin Polak Frank Hempel Henrike Rebl Carmen Zietz Vitezslav Stranak Gerold Lukowski Rainer Hippler Rainer Bader J. Barbara Nebe Klaus‐Dieter Weltmann Karsten Schröder 《Advanced Engineering Materials》2012,14(5):B224-B230
The application of antimicrobial surfaces to titanium alloy (Ti) implants would be beneficial to prevent implant‐associated infections of joint endoprostheses and osteosyntheses. Copper (Cu) could be advantageously applied for this purpose, since it exhibits a well‐known antimicrobial activity and is a trace element in the human body, i.e., it is non‐toxic in small concentrations. This approach was evaluated with two plasma‐based surface modification procedures:
- 1) Implantation of Cu ions into Ti by means of plasma immersion ion implantation (PIII) and
- 2) Coating of Ti surfaces with Cu? Ti films by means of dual high power impulse magnetron sputtering (dual HiPIMS).
986.
Rainer Detsch Olivier Guillon Lothar Wondraczek Aldo R. Boccaccini 《Advanced Engineering Materials》2012,14(3):B38-B44
A soft lithography technique was used to introduce surface patterns on the surface of sintered bioactive glass substrates. Osteoblast‐like MG‐63 cells and rat mesenchymal stem cells (rMSC) seeded on micropatterned bioactive glass surfaces showed different behavior with rMSC exhibiting a better initial attachment than MG‐63 cells. Both cytoskeleton formation and cell spreading of rMSC were supported by the bioactive surfaces. In addition, the structured surfaces seemed to guide MG‐63 cells to a larger extent than rMSC. The in vitro results are important considering the continuous development of bone tissue scaffolds based on silicate bioactive glasses. 相似文献
987.
The reliable fabrication of nanoelectrode pairs with predefined separations in the few nanometer range is an essential prerequisite for future nanoelectronic devices. Here we demonstrate a fine-tuned electron-beam lithographic (EBL) fabrication route which is suitable for defining nanoelectrode pairs with a gap size down to 3 ± 1 nm and with a yield of 55%. This achievement is based on an optimized two-layer resist system in combination with an adopted developer system, as well as on an elaborated nanoelectrode pattern design taking into consideration the EBL inherent proximity effect. Thus, even a structural control in the nanometer scale is achieved in the EBL process. 相似文献
988.
989.
We present the principles of a particle-handling system for the International Space Station (ISS) with which experiments with
astrophysical and planetological applications will be performed. The principle of dust deagglomeration and dispersion was
successfully tested in short-duration microgravity experiments. The flight of the systems on the ISS is planned for 2012. 相似文献
990.
Jörn Müller-Quade Rainer Steinwandt 《Applicable Algebra in Engineering, Communication and Computing》2000,11(1):35-41
Let k(X)/k be a finitely generated purely transcendental extension of fields with transcendence basis X. From a generalization of Lüroth's theorem it is known that all intermediate fields K of k(X)/k with (K/k) = 1 are of the form K = k(f) for some f∈k(X). In this note we give a criterion which allows to decide effectively whether the extension K/k is simple if a finite generating set of K over k is known and computations in K are effective. In the affirmative case a primitive element of K over k is computed.
Received: August 13, 1999; revised version: February 4, 2000 相似文献