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91.
92.
N. Poli M. G. Tarallo M. Schioppo C. W. Oates G. M. Tino 《Applied physics. B, Lasers and optics》2009,97(1):27-33
Existing optical lattice clocks demonstrate a high level of performance but they remain complex experimental devices. In order
to address a wider range of applications including those requiring transportable devices, it will be necessary to simplify
the laser systems and reduce the amount of support hardware. Here we demonstrate two significant steps towards this goal:
demonstration of clock signals from a Sr lattice clock based solely on semiconductor laser technology, and a method for finding
the clock transition (based on a coincidence in atomic wavelengths) that removes the need for extensive frequency metrology
hardware. Moreover, the unexpected high contrast in the signal revealed evidence of density dependent collisions in 88Sr atoms. 相似文献
93.
Uwe D. Zeitner Maria Oliva Frank Fuchs Dirk Michaelis Tino Benkenstein Torsten Harzendorf Ernst-Bernhard Kley 《Applied Physics A: Materials Science & Processing》2012,109(4):789-796
Gratings are essential components in different high performance optical set-ups such as spectrometers in space missions or ultrashort-pulse laser compression arrangements. Often such kinds of applications require gratings operating close to the technological accessible limits of today??s fabrication technology. Typical critical parameters are the diffraction efficiency and its polarization dependency, the wave-front error introduced by the grating, and the stray-light performance. Additionally, space applications have specific environmental requirements and laser application typically demand a high damage threshold. All these properties need to be controlled precisely on rather large grating areas. Grating sizes of 200?mm or even above are not unusual anymore. The paper provides a review on how such high performance gratings can be realized by electron-beam lithography and accompanying technologies. The approaches are demonstrated by different examples. The first example is the design and fabrication of the grating for the Radial-Velocity-Spectrometer of the GAIA-mission of the ESA. The second grating is a reflective pulse compression element with no wavelength resonances due to an optimized design. The last example shows a three level blazed grating in resonance domain with a diffraction efficiency of approximately 86?%. 相似文献
94.
Thorsen TS Madsen KL Dyhring T Bach A Peters D Strømgaard K Rønn LC Gether U 《Combinatorial chemistry & high throughput screening》2011,14(7):590-600
PDZ (PSD-95/Discs-large/ZO-1 homology) domains represent putative targets in several diseases including cancer, stroke, addiction and neuropathic pain. Here we describe the application of a simple and fast screening assay based on fluorescence polarization (FP) to identify inhibitors of the PDZ domain in PICK1 (protein interacting with C kinase 1). We screened 43,380 compounds for their ability to inhibit binding of an Oregon Green labeled C-terminal dopamine transporter peptide (OrG-DAT C13) to purified PICK1 in solution. The assay was highly reliable with excellent screening assay parameters (Z'≈0.7 and Z≈0.6). Out of ~200 compounds that reduced FP to less than 80% of the control wells, six compounds were further characterized. The apparent affinities of the compounds were determined in FP competition binding experiments and ranged from ~5.0 μM to ~193 μM. Binding to the PICK1 PDZ domain was confirmed for five of the compounds (CSC-03, CSC-04, CSC-43, FSC-231 and FSC-240) in a non-fluorescence based assay by their ability to inhibit pull-down of PICK1 by a C-terminal DAT GST fusion protein. CSC-03 displayed the highest apparent affinity (5.0 μM) in the FP assay, and was according to fluorescence resonance energy transfer (FRET) experiments capable of inhibiting the interaction between the C-terminus of the GluR2 subunit of the AMPA-type glutamate receptor and PICK1 in live cells. Additional experiments suggested that CSC-03 most likely is an irreversible inhibitor but with specificity for PICK1 since it did not bind three different PDZ domains of PSD-95. Summarized, our data suggest that FP based screening assays might be a widely applicable tool in the search for small molecule inhibitors of PDZ domain interactions. 相似文献
95.
Samat A. Talipov Bakhtiyar T. Ibragimov Fatkhulla Kh. Tadjimukhamedov Zavkibek G. Tiljakov Alexander J. Blake Tino Hertzsch Jürg Hulliger 《Journal of inclusion phenomena and macrocyclic chemistry》2007,59(3-4):287-292
Gossypol has been obtained in the zeolite-like form by desolvation of the 1:1 unstable solvate with dichloromethane. It demonstrates
a high potential for an uptake of molecular iodine from the environment. In a case of single crystals a stable inclusion compound
(gossypol)8·I2, preserving the crystal structure of the zeolite-like form, has been prepared. The iodine molecules occupy large cavities
of the channels and are inclined as confirmed by the absence of a strong dichroism. The iodine molecules can be removed with
the help of vacuum giving back to the zeolite-like form.
Supplementary Data relating to this article are deposited with the Cambridge Crystallographic Data Centre as supplementary
publication No. CCDC 226180. 相似文献
96.
Lower bounds for the integration error for multivariate functions with mixed smoothness and optimal Fibonacci cubature for functions on the square 下载免费PDF全文
We prove lower bounds for the error of optimal cubature formulae for d‐variate functions from Besov spaces of mixed smoothness in the case , and , where is either the d‐dimensional torus or the d‐dimensional unit cube . In addition, we prove upper bounds for QMC integration on the Fibonacci‐lattice for bivariate periodic functions from in the case , and . A non‐periodic modification of this classical formula yields upper bounds for if . In combination these results yield the correct asymptotic error of optimal cubature formulae for functions from and indicate that a corresponding result is most likely also true in case . This is compared to the correct asymptotic of optimal cubature formulae on Smolyak grids which results in the observation that any cubature formula on Smolyak grids can never achieve the optimal worst‐case error. 相似文献
97.
98.
Summary We report the measurements of the3
D(3s4d)-3
P(3s3p)3
D(3s5d)-3
P(3s3p), and3
P(3p
2)-3
P(3s3p) transition frequency of MgI, the fine-structure separation and isotope shift between24Mg and26Mg. The measurements have been performed in a metastable atomic beam; a good agreement is found for data already existing
in the literature. The accuracy of the measurements reported in this paper is mainly limited by the Doppler broadening of
theI
2 transitions used as a reference and by the precision in the knowledge of the related wavelengths. 相似文献
99.
We prove new optimal bounds for the error of numerical integration in bivariate Besov spaces with dominating mixed order r. The results essentially improve on the so far best known upper bound achieved by using cubature formulas taking points from a sparse grid. Motivated by Hinrichs’ observation that Hammersley type point sets provide optimal discrepancy estimates in Besov spaces with mixed smoothness on the unit square, we directly study quasi-Monte Carlo integration on such point sets. As the main tool we prove the representation of a bivariate periodic function in a piecewise linear tensor Faber basis. This allows for optimal worst case estimates of the QMC integration error with respect to Besov spaces with dominating mixed smoothness up to order r<2. The results in this paper are the first step towards sharp results for spaces with arbitrarily large mixed order on the d-dimensional unit cube. In fact, in contrast to Fibonacci lattice rules, which are also practicable in this context, the QMC methods used in this paper have a proper counterpart in d dimensions. 相似文献
100.
Electro-magnetic acoustic transducers (EMATs) are intended as non-contact and non-destructive ultrasound transducers for metallic material. The transmitted intensities from EMATS are modest, particularly at notable lift off distances. Some time ago a concept for a “coil only EMAT” was presented, without static magnetic field. In this contribution, such compact “coil only EMATs” with effective areas of 1–5 cm2 were driven to excessive power levels at MHz frequencies, using pulsed power technologies. RF induction currents of 10 kA and tens of Megawatts are applied. With increasing power the electroacoustic conversion efficiency also increases. The total effect is of second order or quadratic, therefore non-linear and progressive, and yields strong ultrasound signals up to kW/cm2 at MHz frequencies in the metal. Even at considerable lift off distances (cm) the ultrasound can be readily detected. Test materials are aluminum, ferromagnetic steel and stainless steel (non-ferromagnetic). Thereby, most metal types are represented. The technique is compared experimentally with other non-contact methods: laser pulse induced ultrasound and spark induced ultrasound, both damaging to the test object’s surface. At small lift off distances, the intensity from this EMAT concept clearly outperforms the laser pulses or heavy spark impacts. 相似文献