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21.
W. Weiland R. Otto M. Rösseler H. Koch 《Isotopes in environmental and health studies》2013,49(11):448-452
Zur Reinigung 14C-markierter Kohlenwasserstoffe wird ein präparativer Gaschromatograph verwendet. Die analytische Kontrolle vor und nach der pröparativen Abtrennung erfolgt mit einem Radiogaschromatographen. Technische Einzelheiten beider Geräte sowie einige präparative Tremmimgem werden beschrieben. 相似文献
22.
23.
Weiland JD Faraji B Greenberg RJ Humayun MS Shellock FG 《Magnetic resonance imaging》2012,30(3):382-389
Objective
The objective was to evaluate magnetic resonance imaging (MRI) issues (magnetic field interactions, heating, artifacts and functional alterations) at 1.5 T and 3 T for the Argus II Retinal Prosthesis (Second Sight Medical Products, Sylmar, CA, USA).Materials and Methods
Standardized protocols were used to assess magnetic field interactions (translational attraction and torque; 3 T, worst case), MRI-related heating (1.5 and 3 T), artifacts (3 T; worst case) and functional changes (1.5 and 3 T) associated with MRI.Results
The magnetic field interactions were acceptable. MRI-related heating, which was studied at a relatively high, MR system-reported whole body averaged specific absorption rates, will not pose a hazard to the patient under the conditions used for testing. While artifacts were “moderate” in relation to the dimensions of the Argus II Retinal Prosthesis, optimization of MRI parameters can reduce the size of the artifacts. Exposures to MRI conditions at 1.5 and 3 T did not damage or alter the functional aspects of the Argus II Retinal Prosthesis.Conclusions
In consideration of the test results, a patient with the Argus II Retinal Prosthesis may undergo MRI at 1.5 T or 3 T when specific guidelines and MRI conditions are followed, including those advised by the manufacturer. 相似文献24.
A framework for performing dynamic mesh adaptation with the discontinuous Galerkin method (DGM) is presented. Adaptations include modifications of the local mesh step size (h-adaptation) and the local degree of the approximating polynomials (p-adaptation) as well as their combination. The computation of the approximation within locally adapted elements is based on projections between finite element spaces (FES), which are shown to preserve an upper limit of the electromagnetic energy. The formulation supports high level hanging nodes and applies precomputation of surface integrals for increasing computational efficiency. Error and smoothness estimates based on interface jumps are presented and applied to the fully hp-adaptive simulation of two examples in one-dimensional space. A full wave simulation of electromagnetic scattering from a radar reflector demonstrates the applicability to large scale problems in three-dimensional space. 相似文献
25.
The interaction of a vortical unsteady flow with structures is often encountered in engineering applications. Such flow structure
interactions (FSI) can be responsible for generating significant loads and can have many detrimental structural and acoustic
side effects, such as structural fatigue, radiated noise and even catastrophic results. Amongst the different types of FSI,
the parallel blade–vortex interaction (BVI) is the most common, often encountered in helicopters and propulsors. In this work,
we report on the implementation of leading edge blowing (LEB) active flow control for successfully minimizing the parallel
BVI. Our results show reduction of the airfoil vibrations up to 38% based on the root-mean-square of the vibration velocity
amplitude. This technique is based on displacing an incident vortex using a jet issued from the leading edge of a sharp airfoil
effectively increasing the stand-off distance of the vortex from the body. The effectiveness of the method was experimentally
analyzed using time-resolved digital particle image velocimetry (TRDPIV) recorded at an 800 Hz rate, which is sufficient to
resolve the spatio-temporal dynamics of the flow field and it was combined with simultaneous accelerometer measurements of
the airfoil, which was free to oscillate in a direction perpendicular to the freestream. Analysis of the flow field spectra
and a Proper Orthogonal Decomposition (POD) of the TRDPIV data of the temporally resolved planar flow fields indicate that
the LEB effectively modified the flow field surrounding the airfoil and increased the convecting vortices stand-off distance
for over half of the airfoil chord length. It is shown that LEB also causes a redistribution of the flow field spectral energy
over a larger range of frequencies. 相似文献
26.
P. Lemmer M. Gunkel D. Baddeley R. Kaufmann A. Urich Y. Weiland J. Reymann P. Müller M. Hausmann C. Cremer 《Applied physics. B, Lasers and optics》2008,93(1):1-12
Far-field fluorescence techniques based on the precise determination of object positions have the potential to circumvent
the optical resolution limit of direct imaging given by diffraction theory. In order to use localization to obtain structural
information far below the diffraction limit, the ‘point-like’ components of the structure have to be detected independently,
even if their distance is lower than the conventional optical resolution limit. This goal can be achieved by exploiting various
photo-physical properties of the fluorescence labeling (‘spectral signatures’). In first experiments, spectral precision distance
microscopy/spectral position determination microscopy (SPDM) was limited to a relatively small number of components to be
resolved within the observation volume. Recently, the introduction of photoconvertable molecules has dramatically increased
the number of components which can be independently localized. Here, we present an extension of the SPDM concept, exploiting
the novel spectral signature offered by reversible photobleaching of fluorescent proteins. In combination with spatially modulated
illumination (SMI) microscopy, at the present stage, we have achieved an estimated effective optical resolution of approximately
20 nm in the lateral and 50 nm in the axial direction, or about 1/25th–1/10th of the exciting wavelength. 相似文献
27.
28.
Weiland TR Kundu S Trent JT Hoy JA Hargrove MS 《Journal of the American Chemical Society》2004,126(38):11930-11935
Hexacoordinate hemoglobins are a class of proteins that exhibit reversible bis-histidyl coordination of the heme iron while retaining the ability to bind exogenous ligands. One hypothesis for their physiological function is that they scavenge nitric oxide, a reaction that oxidizes the protein and requires reduction of the heme iron to continue. Reduction kinetics of hexacoordinate hemoglobins, including human neuroglobin and cytoglobin, and those from Synechocystis and rice, are compared to myoglobin, soybean leghemoglobin, and several relevant mutant proteins. In all cases, bis-histidyl coordination greatly increases the rate of reduction by sodium dithionite when compared to pentacoordinate hemoglobins. In myoglobin and leghemoglobin, reduction is limited by the rate constant for electron transfer, whereas in the hexacoordinate hemoglobins reduction is limited only by bimolecular binding of the reductant. These results can be explained by differences in the reorganization energy for reduction between hexacoordinate and pentacoordinate hemoglobins. 相似文献
29.
M. Popp J. Contzen H. Immendorff D. P. Mileff N. E. Pestow F. B. Carpenter R. O. Powell Z. I. Kertész F. J. Kokoski A. W. Clark H. A. Pieters M. J. Mannes K. J. B. de Kleermaeker G. H. C. van Bers J. Haas F. Alten H. Weiland J. S. Teletow S. P. Faraschjan W. I. Tichonenko 《Analytical and bioanalytical chemistry》1937,110(1-2):53-60
30.
M. Popp J. Contzen H. Immendorff D. P. Mileff N. E. Pestow F. B. Carpenter R. O. Powell Z. I. Kertész F. J. Kokoski A. W. Clark H. A. Pieters M. J. Mannes K. J. B. de Kleermaeker G. H. C. van Bers J. Haas F. Alten H. Weiland J. S. Teletow S. P. Faraschjan und W. I. Tichonenko 《Fresenius' Journal of Analytical Chemistry》1937,110(1-2):53-60
Ohne Zusammenfassung 相似文献