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51.
Mercuration of η5-cyclopentadienyl-η4-tetraphenylcyclobutadienecobalt, followed by transmetalation with n-butyllithium and reaction of the lithium derivative with benzophenone gave η4-Ph4C4Coη5-C5H4CPh2OH. Treatment of this alcohol produced the [η4-Ph4C4CoC5H4CP2]+ cation. This species reacted as a carbon electrophile with methanol, monomethylamine and N-methylpyrrole, as a cobalt electrophile with N,N-dimethylaniline and anisole. In the latter process the C5H4CPh2 ligand was displaced and the η6-arene-η4-tetraphenylcyclobutadienecobalt complexes were formed. Similar reactions with benzene, toluene and mesitylene proceeded only in the presence of aluminum chloride. The bonding in the cation is discussed on the basis of this chemistry and 13C NMR studies. 相似文献
52.
The post-translational modifications of the 96 kDa protein dynamin A from Dictyostelium discoideum were analyzed using Q-TOF mass spectrometry. The accurate molecular mass of the intact protein revealed a covalent modification causing an additional mass of 42 Da. The modification could be identified as N-terminal acetylation by tandem mass spectrometry. Extracted ion chromatograms for the a(1) and b(1) ion of the tryptic T1 peptide were used to detect the acetylated peptide within 54 nanoelectrospray ionization tandem mass spectra. Owing to the accurate molecular mass of the intact protein, additional covalent modifications could be excluded. In addition to the covalent modification, the domain structure of dynamin A was determined by applying a combination of limited proteolysis, sodium dodecylsulfate polyacrylamide gel electrophoresis, automated tandem mass spectrometry and protein database searching. 相似文献
53.
Dietmar Rahner Stefan Machill Heike Schlörb Kerstin Siury Matthias Kloss Waldfried Plieth 《Journal of Solid State Electrochemistry》1998,2(2):78-84
An overview is given of intercalation materials for both the negative and the positive electrodes of lithium batteries, including
the results of our own research. As well as lithium metal as a negative electrode, we consider insertion materials based on
aluminium alloys. In the case of the positive electrode metal-oxides based on manganese, nickel and cobalt are discussed.
Received: 27 May 1997 / Accepted: 30 July 1997 相似文献
54.
Scaffold based tissue engineering strategies use cells, biomolecules and a scaffold to promote the repair and regeneration of tissues. Although scaffold-based tissue engineering approaches are being actively developed, most are still experimental, and it is not yet clear what defines an ideal scaffold/cell construct. Solid free form fabrication (SFF) techniques can precisely control matrix architecture (size, shape, interconnectivity, branching, geometry and orientation). The SFF methods enable the fabrication of scaffolds with various designs and material compositions, thus providing a control of mechanical properties, biological effects and degradation kinetics. This paper reviews the application of micro-robotics and MEMS-based fabrication techniques for scaffold design and fabrication. It also presents a novel robotic technique to fabricate scaffold/cell constructs for tissue engineering by the assembly of microscopic building blocks. 相似文献
55.
Kocher N Henn J Gostevskii B Kost D Kalikhman I Engels B Stalke D 《Journal of the American Chemical Society》2004,126(17):5563-5568
The concept of hypervalency in molecules, which hold more than eight valence electrons at the central atom, still is a topic of constant debate. There is general interest in silicon compounds with more than four substituents at the central silicon atom. The dispute, whether this silicon is hypervalent or highly coordinated, is enlightened by the first experimental charge density determination and subsequent topological analysis of three different highly polar Si-E (E = N, O, F) bonds in a hexacoordinated compound. The experiment reveals predominantly ionic bonding and much less covalent contribution than commonly anticipated. For comparison gas-phase ab initio calculations were performed on this compound. The results of the theoretical calculations underline the findings of the experiment. 相似文献
56.
Leitner Christian Hess Johann Galhaup Christiane Ludwig Roland Nidetzky Bernd Kulbe Klaus D. Haltrich Dietmar 《Applied biochemistry and biotechnology》2002,98(1-9):497-507
The wood-degrading fungus Trametes multicolor secretes several laccase isoforms when grown on a simple medium containing copper in the millimolar range for stimulating
laccase synthesis. The main isoenzyme laccase II was purified to apparent homogeneity from the culture supernatant by using
anion-exchange chromatography and gel filtration. Laccase II is a monomeric glycoprotein with a molecular mass of 63 kDa as
determined by sodium dodecylsulfate polyacrylamide gel electrophoresis, contains 18% glycosylation, and has a pI of 3.0. It oxidizes a variety of phenolic substrates as well as ferrocyanide and iodide. The pH optimum depends on the substrate
employed and shows a bell-shaped pH activity profile with an optimum of 4.0 to 5.0 for the phenolic substrates, while the
nonphenolic substrates ferrocyanide and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonate) show a monotonic pH profile with
a rate decreasing with increasing pH. 相似文献
57.
58.
Elvira Welzig Harald Pichler Rudolf Krska Dietmar Knopp Reinhard Niessner 《International journal of environmental analytical chemistry》2013,93(3-4):279-288
Abstract The development of an indirect competitive enzyme immunoassay for the sulfonylurea herbicide metsulfuron-methyl (MSM) is described. In contrast to traditional antibody generation in mammals, this extremely sensitive method is based on chicken egg yolk antibodies (IgY). They were raised in laying hens using an MSM-derivative-BSA hapten as immunogen. With a 1:10000 dilution of the antibody solution and a coating antigen (MSM-derivative-KLH) concentration of 10 μg L?1 the IC50 value achieved for the target analyte was 0.4 μg L?1. The least detectable dose was established at 13 ng L?1. Cross-reactivity was tested with 5 structurally related compounds, where only sulfometuron showed a significant binding. The ELISA was tested with spiked tap and surface water samples. This paper, for the first time, demonstrates the production of high-affinity IgY antibodies for a herbicide compound. 相似文献
59.
Stem cell research is one of the most promising fields of modern biomedical research and regenerative medicine. Limited availability and ethical concerns suggest the renouncement of embryonic stem cells (ESCs), thus raising the need for more efficient procedures for the generation of stem cells, ideally through reprogramming of mammalian cells. The small molecule N-benzyl-2-(pyrimidin-4′-ylamino)-thiazole-4-carboxamide (thiazovivin) is known to improve the generation of human induced pluripotent stem cells (iPSCs) from human fibroblasts. We herein describe a highly efficient procedure for the synthesis of thiazovivin over just five steps, which should be suitable for a large-scale application, and the first x-ray crystal structure of the target compound. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.] 相似文献
60.