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61.
Wang YJ Eardley M Knappe S Moreland J Hollberg L Kitching J 《Physical review letters》2006,97(22):227602
We demonstrate a direct resonant interaction between the mechanical motion of a mesoscopic resonator and the spin degrees of freedom of a sample of neutral atoms in the gas phase. This coupling, mediated by a magnetic particle attached to the tip of the miniature mechanical resonator, excites a coherent precession of the atomic spins about a static magnetic field. The novel coupled atom-resonator system may enable development of low-power, high-performance sensors, and enhance research efforts connected with the manipulation of cold atoms, quantum control, and high-resolution microscopy. 相似文献
62.
Edna Bode Antje K. Heinrich Merle Hirschmann Desalegne Abebew Yan‐Ni Shi Tien Duy Vo Frank Wesche Yi‐Ming Shi Peter Grün Svenja Simonyi Nadine Keller Yvonne Engel Sebastian Wenski Reuel Bennet Sophie Beyer Iris Bischoff Anthony Buaya Sophie Brandt Ibrahim Cakmak Harun imen Simone Eckstein Denia Frank Robert Fürst Martin Gand Gerd Geisslinger Selcuk Hazir Marina Henke Ralf Heermann Virginie Lecaudey Wilhelm Schfer Susanne Schiffmann Anja Schüffler Rebecca Schwenk Marisa Skaljac Eckhard Thines Marco Thines Thomas Ulshfer Andreas Vilcinskas Thomas A. Wichelhaus Helge B. Bode 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):19133-19139
Natural products (NPs) from microorganisms have been important sources for discovering new therapeutic and chemical entities. While their corresponding biosynthetic gene clusters (BGCs) can be easily identified by gene‐sequence‐similarity‐based bioinformatics strategies, the actual access to these NPs for structure elucidation and bioactivity testing remains difficult. Deletion of the gene encoding the RNA chaperone, Hfq, results in strains losing the production of most NPs. By exchanging the native promoter of a desired BGC against an inducible promoter in Δhfq mutants, almost exclusive production of the corresponding NP from the targeted BGC in Photorhabdus, Xenorhabdus and Pseudomonas was observed including the production of several new NPs derived from previously uncharacterized non‐ribosomal peptide synthetases (NRPS). This easyPACId approach (easy Promoter Activated Compound Identification) facilitates NP identification due to low interference from other NPs. Moreover, it allows direct bioactivity testing of supernatants containing secreted NPs, without laborious purification. 相似文献
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65.
Stefan Helber Katja Schimmelpfeng Raik Stolletz Svenja Lagershausen 《Annals of Operations Research》2011,182(1):193-211
This paper presents a linear programming approach to analyze and optimize flow lines with limited buffer capacities and stochastic
processing times. The basic idea is to solve a huge but simple linear program that models an entire simulation run of a multi-stage
production process in discrete time, to determine a production rate estimate. As our methodology is purely numerical, it offers
the full modeling flexibility of stochastic simulation with respect to the probability distribution of processing times. However,
unlike discrete-event simulation models, it also offers the optimization power of linear programming and hence allows us to
solve buffer allocation problems. We show under which conditions our method works well by comparing its results to exact values
for two-machine models and approximate simulation results for longer lines. 相似文献
66.
Dr. Thiruvancheril G. Gopakumar Dr. Matthias Bernien Holger Naggert Dr. Francesca Matino Christian F. Hermanns Dr. Alexander Bannwarth Svenja Mühlenberend Alex Krüger Dennis Krüger Fabian Nickel Waldemar Walter Prof. Dr. Richard Berndt Prof. Dr. Wolfgang Kuch Prof. Dr. Felix Tuczek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(46):15702-15709
Submono‐, mono‐ and multilayers of the Fe(II) spin‐crossover (SCO) complex [Fe(bpz)2(phen)] (bpz=dihydrobis(pyrazolyl)borate, phen=1,10‐phenanthroline) have beenprepared by vacuum deposition on Au(111) substrates and investigated with near edge X‐ray absorption fine structure (NEXAFS) spectroscopy and scanning tunneling microscopy (STM). As evidenced by NEXAFS, molecules of the second layer exhibit a thermal spin crossover transition, although with a more gradual characteristics than in the bulk. For mono‐ and submonolayers of [Fe(bpz)2(phen)] deposited on Au(111) substrates at room temperature both NEXAFS and STM indicate a dissociation of [Fe(bpz)2(phen)] on Au(111) into four‐coordinate complexes, [Fe(bpz)2], and phen molecules. Keeping the gold substrate at elevated temperatures ordered monolayers of intact molecules of [Fe(bpz)2(phen)] are formed which can be spin‐switched by electron‐induced excited spin‐state trapping (ELIESST). 相似文献
67.
Dr. Isabelle Marie Daubit Svenja Wortmann Dr. Daniel Siegmund Prof. Dr. Stephan Hahn Prof. Dr. Patrick Nuernberger Prof. Dr. Nils Metzler-Nolte 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(22):6783-6794
Complexes of RhI and IrI of the [M(COD)(NHC)X] type (where M=Rh or Ir, COD=1,5-cyclooctadiene, NHC=N-heterocyclic carbene, and X=halide) have recently shown promising cytotoxic activities against several cancer cell lines. Initial mechanism of action studies provided some knowledge about their interaction with DNA and proteins. However, information about their cellular localization remains scarce owing to luminescence quenching within this complex type. Herein, the synthesis of two rare examples of luminescent RhI and IrI [M(COD)(NHC)I] complexes with 1,8-naphthalimide-based emitting ligands is reported. All new complexes are comprehensively characterized, including with single-crystal X-ray structures. Steric crowding in one derivative leads to two distinct rotamers in solution, which apparently can be distinguished both by pronounced NMR shifts and by their respective spectral and temporal emission signatures. When the photophysical properties of these new complexes are exploited for cellular imaging in HT-29 and PT-45 cancer cell lines, it is demonstrated that the complexes accumulate predominantly in the endoplasmic reticulum, which is an entirely new finding and provides the first insight into the cellular localization of such IrI(NHC) complexes. 相似文献
68.
Ruthenium/Imidazolylphosphine Catalysis: Hydrogenation of Aliphatic and Aromatic Nitriles to Form Amines 下载免费PDF全文
Svenja Werkmeister Dr. Kathrin Junge Bianca Wendt Dr. Anke Spannenberg Dr. Haijun Jiao Christoph Bornschein Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(15):4227-4231
A convenient and efficient catalyst system for the hydrogenation of aliphatic nitriles towards the corresponding primary amines in high to excellent yields is presented. In addition, aromatic nitriles are reduced smoothly, too. The use of low catalyst loadings and molecular hydrogen make this protocol an attractive methodology. 相似文献
69.
A One‐Pot Cascade Reaction Combining an Encapsulated Decarboxylase with a Metathesis Catalyst for the Synthesis of Bio‐Based Antioxidants 下载免费PDF全文
Dr. Álvaro Gómez Baraibar Dennis Reichert Dr. Carolin Mügge Svenja Seger Prof. Dr. Harald Gröger Prof. Dr. Robert Kourist 《Angewandte Chemie (International ed. in English)》2016,55(47):14823-14827
The combination of enzymes with traditional chemical catalysts unifies the high selectivity of the former with the versatility of the latter. A major challenge of this approach is the difference in the optimal reaction conditions for each catalyst type. In this work, we combined a cofactor‐free decarboxylase with a ruthenium metathesis catalyst to produce high‐value antioxidants from bio‐based precursors. As suitable ruthenium catalysts did not show satisfactory activity under aqueous conditions, the reaction required the use of an organic solvent, which in turn significantly reduced enzyme activity. Upon encapsulation of the decarboxylase in a cryogel, the decarboxylation could be conducted in an organic solvent, and the recovery of the enzyme after the reaction was facilitated. After an intermediate drying step, the subsequent metathesis in pure organic solvent proved to be straightforward. The synthetic utility of the cascade was demonstrated by the synthesis of the antioxidant 4,4′‐dihydroxystilbene in an overall yield of 90 %. 相似文献