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221.
222.
This paper investigates the benefit of unsteady blowing actuation over a two-dimensional (2D) airfoil specially designed for wind turbine applications. The experiments were carried out in Syracuse University’s anechoic wind tunnel, both with and without large-scale unsteadiness in the free stream generated by a 2D cylinder upstream of the airfoil. By analyzing both surface pressure through wavelet analysis and Particle Image Velocimetry (PIV) velocity field measurements, we found a drastic change in the flow physics and the aerodynamic loading on the airfoil between steady and unsteady free-stream conditions. When there was no large-scale unsteadiness introduced in the flow, under open-loop flow control conditions with unsteady blowing, the leading-edge separation was delayed and the maximum lift coefficient was increased. For the cases where large-scale unsteadiness was introduced into the flow, the experiments showed that both open-loop and closed-loop control cases were capable of reducing load fluctuations by a measurable amount. However, only the closed-loop control case that utilized dynamic surface pressure information from the airfoil suction side near the leading edge was capable of consistently mitigating the fluctuating load. 相似文献
223.
Klaudia Radula‐Janik Teobald Kupka Krzysztof Ejsmont Zdzislaw Daszkiewicz Stephan P. A. Sauer 《Magnetic resonance in chemistry : MRC》2013,51(10):630-635
Structures of selected 3,6‐dihalogeno‐N‐alkyl carbazole derivatives were calculated at the B3LYP/6‐311++G(3df,2pd) level of theory, and their 13C nuclear magnetic resonance (NMR) isotropic shieldings were predicted using density functional theory (DFT). The model compounds contained 9H, N‐methyl and N‐ethyl derivatives. The relativistic effect of Br and I atoms on nuclear shieldings was modeled using the spin–orbit zeroth‐order regular approximation (ZORA) method. Significant heavy atom shielding effects for the carbon atom directly bonded with Br and I were observed (~?10 and ~?30 ppm while the other carbon shifts were practically unaffected). The decreasing electronegativity of the halogen substituent (F, Cl, Br, and I) was reflected in both nonrelativistic and relativistic NMR results as decreased values of chemical shifts of carbon atoms attached to halogen (C3 and C6) leading to a strong sensitivity to halogen atom type at 3 and 6 positions of the carbazole ring. The predicted NMR data correctly reproduce the available experimental data for unsubstituted N‐alkylcarbazoles. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
224.
Pharmacokinetic study of amoxicillin in human plasma by solid‐phase microextraction followed by high‐performance liquid chromatography–triple quadrupole mass spectrometry 下载免费PDF全文
Malgorzata Szultka Rafal Krzeminski Justyna Walczak Marek Jackowski Boguslaw Buszewski 《Biomedical chromatography : BMC》2014,28(2):255-264
Sensitive and selective analytical procedures based on high‐performance liquid chromatography with mass spectrometric detection were developed for the determination of amoxicillin in human plasma samples. Samples were prepared by applying in‐house manufactured molecularly imprinted solid‐phase microextraction probes. The detection of target compounds was performed in multiple reaction monitoring mode. The multiple reaction monitoring detection was operated in the positive electrospray ionization mode using the transitions of m/z 366 ([M + H]+) → 349 for amoxicillin and m/z 390 ([M + H]+) → 372 for gemifloxacin. The method was validated with precision within 15% relative standard deviation and accuracy within 15% relative error. The method was successfully applied to study of the pharmacokinetics of amoxicillin in human plasma after oral administration of amoxicillin. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
225.
Zurek E Pickard CJ Walczak B Autschbach J 《The journal of physical chemistry. A》2006,110(43):11995-12004
NMR chemical shifts were calculated for semiconducting (n,0) single-walled carbon nanotubes (SWNTs) with n ranging from 7 to 17. Infinite isolated SWNTs were calculated using a gauge-including projector-augmented plane-wave (GIPAW) approach with periodic boundary conditions and density functional theory (DFT). In order to minimize intertube interactions in the GIPAW computations, an intertube distance of 8 A was chosen. For the infinite tubes, we found a chemical shift range of over 20 ppm for the systems considered here. The SWNT family with lambda = mod(n, 3) = 0 has much smaller chemical shifts compared to the other two families with lambda = 1 and lambda = 2. For all three families, the chemical shifts decrease roughly inversely proportional to the tube's diameter. The results were compared to calculations of finite capped SWNT fragments using a gauge-including atomic orbital (GIAO) basis. Direct comparison of the two types of calculations could be made if benzene was used as the internal (computational) reference. The NMR chemical shifts of finite SWNTs were found to converge very slowly, if at all, to the infinite limit, indicating that capping has a strong effect (at least for the (9,0) tubes) on the calculated properties. Our results suggest that (13)C NMR has the potential for becoming a useful tool in characterizing SWNT samples. 相似文献
226.
Silvia Jordans Saša Jenko-Kokalj Nicole M Kühl Sofia Tedelind Wolfgang Sendt Dieter Brömme Dušan Turk Klaudia Brix 《BMC biochemistry》2009,10(1):23-15
Background
Cysteine cathepsins are known to primarily cleave their substrates at reducing and acidic conditions within endo-lysosomes. Nevertheless, they have also been linked to extracellular proteolysis, that is, in oxidizing and neutral environments. Although the impact of reducing or oxidizing conditions on proteolytic activity is a key to understand physiological protease functions, redox conditions have only rarely been considered in routine enzyme activity assays. Therefore we developed an assay to test for proteolytic processing of a natural substrate by cysteine cathepsins which accounts for redox potentials and pH values corresponding to the conditions in the extracellular space in comparison to those within endo-lysosomes of mammalian cells. 相似文献227.
Malgorzata Walczak Mohamed Oujja José Francisco Marco Mikel Sanz Marta Castillejo 《Applied Physics A: Materials Science & Processing》2008,93(3):735-740
Promising applications of TiO2 nanostructures include the development of optical devices, sensors, photocatalysts and self-cleaning coatings. In view of
their importance, research on the synthesis of nanosized TiO2 is a particularly active field. In this work we report on the investigation of the effect of laser irradiation wavelength
(Q-switched Nd:YAG laser at 532, 355 and 266 nm), the temperature of the substrate and the atmosphere of deposition (vacuum,
Ar and O2) that are suitable for obtaining nanostructured deposits from TiO2 sintered targets. The ablation plume emission is characterized with spectral and temporal resolution by optical emission
spectroscopy (OES), while the surface morphology and chemical states of the material deposited on a Si (100) substrate are
examined by environmental scanning electron microscopy (ESEM) and atomic force microscopy (AFM) and by X-ray photoelectron
spectroscopy (XPS), respectively. Deposits with nanostructured morphology with grain size down to 40 nm and keeping the stoichiometry
of the targets were obtained at high temperature, while the highest concentration of particulates was observed at the longest
laser wavelength of 532 nm on a substrate heated up to 650°C. In situ characterization of the ablation plume, carried out
by OES, indicated the presence of emissions assigned to Ti I, Ti II and O I. 相似文献
228.
Qing Qin Yun Zhao Max Schmallegger Tobias Heil Johannes Schmidt Ralf Walczak Georg Gescheidt‐Demner Haijun Jiao Martin Oschatz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):13235-13240
The electrochemical conversion of N2 at ambient conditions using renewably generated electricity is an attractive approach for sustainable ammonia (NH3) production. Considering the chemical inertness of N2, rational design of efficient and stable catalysts is required. Therefore, in this work, it is demonstrated that a C‐doped TiO2/C (C‐TixOy/C) material derived from the metal–organic framework (MOF) MIL‐125(Ti) can achieve a high Faradaic efficiency (FE) of 17.8 %, which even surpasses most of the established noble metal‐based catalysts. On the basis of the experimental results and theoretical calculations, the remarkable properties of the catalysts can be attributed to the doping of carbon atoms into oxygen vacancies (OVs) and the formation of Ti?C bonds in C‐TixOy. This binding motive is found to be energetically more favorable for N2 activation compared to the non‐substituted OVs in TiO2. This work elucidates that electrochemical N2 reduction reaction (NRR) performance can be largely improved by creating catalytically active centers through rational substitution of anions into metal oxides. 相似文献
229.
Multicomponent condensation of N-diphenylphosphinoylimines, alkynes, zirconocene hydrochloride, and diiodomethane provides a rapid access to omega-unsaturated dicyclopropylmethylamines. These novel building blocks are converted into heterocyclic 5-azaspiro[2.4]heptanes, 5-azaspiro-[2.5]octanes, and 5-azaspiro[2.6]nonanes by means of selective ring-closing metathesis, epoxide opening, or reductive amination. The resulting functionalized pyrrolidines, piperidines, and azepines are scaffolds of considerable relevance for chemistry-driven drug discovery. 相似文献
230.
P. Caban J. Rembieliński K. A. Smoliński Z. Walczak 《International Journal of Theoretical Physics》2003,42(5):1045-1052
Einstein—Podolsky—Rosen spin correlations in the framework of nonrelativistic quantum mechanics for moving observers are calculated. The measurements are performed in bounded regions of space (detectors), not necessarily simultaneously. The resulting correlation function depends not only on the directions of spin measurements but also on the relative velocity of the observers. 相似文献