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Pannert W.,Aalen University of Applied Sciences
Applied Acoustics | Year: 2011

The spatial smoothing (SS) technique has been proved to be effective in decorrelating coherent signals by restoring the rank of the signal covariance matrix R. Averaging the covariance matrices of subarrays of the original array, is a technique which increases the rank of the smoothed matrix RSS. Algorithms like MUSIC or Capon, which rely on the use of the signal covariance matrix R and fail in the case of correlated sources, can be applied to scenarios with correlated sources after spatial smoothing. However, SS is most practically applied to uniformly spaced arrays or to arrays which have a translational symmetry. In addition the formulation is strictly applicable only to such farfield conditions, where the incoming waves are plane waves and the steering vectors to the sources of the different subarrays are identical. These conditions are not fulfilled in the nearfield. Spatial smoothing is now applied with an acoustic camera in the nearfield and it is shown that up to some limits this technique is applicable. Effects/limitations are studied using simulation and measurements with several Beamforming algorithms (MUSIC, Capon and Orthogonal Beamforming) are carried out. The results demonstrate the benefits of SS even in the nearfield up to some limits, which are given through the distance of the different subarrays in comparison to the spatial resolution of the Beamforming algorithm. Especially at lower frequencies SS in connection with MUSIC- or Capon-Beamforming give better resolution in comparison to D + S Beamforming. © 2011 Elsevier Ltd. All rights reserved. Source


Tiritiris I.,Aalen University of Applied Sciences
Acta Crystallographica Section E: Structure Reports Online | Year: 2013

In the title solvated salt, C11H28N4 2+·2C24H20B -·2C3H6O, the C - N bond lengths in the central CN3 unit of the guanidinium ion are 1.3331 (16), 1.3407 (16) and 1.3454 (16) Å, indicating partial double-bond character in each. The central C atom is bonded to the three N atoms in a nearly ideal trigonal-planar geometry [N - C - N angles = 118.96 (11), 120.51 (12) and 120.53 (11)°] and the positive charge is delocalized in the CN3 plane. The bonds between the N atoms and the terminal C-methyl groups of the guanidinium moiety all have values close to a typical single bond [1.4601 (16)-1.4649 (16) Å]. In the crystal, the guanidinium ion is connected by N - H⋯O and C - H⋯O hydrogen bonds with the acetone molecules. C - H⋯π interactions are present between the guanidinium H atoms and the phenyl rings of both tetraphenylborate ions. The phenyl rings form aromatic pockets, in which the guanidinium ions are embedded. © 2013 Ioannis Tiritiris. Source


Tiritiris I.,Aalen University of Applied Sciences
Acta Crystallographica Section E: Structure Reports Online | Year: 2013

In the crystal structure of the title salt, C12H30N4 2+·2C24H20B-, the C - N bond lengths in the central CN3 unit of the guanidinium ion are 1.3388 (17), 1.3390 (16) and 1.3540 (17) Å, indicating partial double-bond character in each. The central C atom is bonded to the three N atoms in a nearly ideal trigonal-planar geometry and the positive charge is delocalized in the CN3 plane. The bonds between the N atoms and the terminal C-methyl groups of the guanidinium moiety, all have values close to a typical single bond [1.4630 (16)-1.4697 (17) Å]. C - H⋯π interactions are present between the guanidinium H atoms and the phenyl C atoms of one tetraphenylborate ion. The phenyl rings form a kind of aromatic pocket, in which the guanidinium ion is embedded. Source


Ongay S.,Institute of Organic Chemistry CSIC | Neususs C.,Aalen University of Applied Sciences
Analytical and Bioanalytical Chemistry | Year: 2010

Human AGP is an acidic glycoprotein mainly produced by liver that presents a high degree of heterogeneity. It can present different amino acid sequences and has five N-glycosylation sites leading to a wide range of different protein isoforms. AGP structure and composition has been widely studied due to its drug-binding behavior and relation with disease. However, so far, the characterization has been performed only on protein fragments, i.e., the peptide or glycan level. Here, the analysis of intact human AGP purified from human serum is performed by capillary electrophoresis-time-of-flight mass spectrometry. In this way, it is possible to characterize more than 150 human AGP isoforms, differing both in the amino acid sequence and in the glycosylation. The detected masses could be attributed unequivocally to an overall composition based on the combination of the analysis of the released glycans and the characterization of the deglycosylated protein. Different AGP samples purified from human serum were characterized and compared. High inter-individual variability among AGP isoforms expression was observed. The presented method enables for the first time clinical studies based on detailed isoform distribution of intact glycoproteins. © 2010 Springer-Verlag. Source


Van Pinxteren D.,Leibniz Institute For Tropospharenforschung Tropos | Neususs C.,Aalen University of Applied Sciences | Herrmann H.,Leibniz Institute For Tropospharenforschung Tropos
Atmospheric Chemistry and Physics | Year: 2014

Dicarboxylic acids (DCAs) are among the most abundant organic compounds observed in atmospheric aerosol particles and have been extensively studied at many places around the world. The importance of the various primary sources and secondary formation pathways discussed in the literature is often difficult to assess from field studies, though. In the present study, a large data set of size-resolved DCA concentrations from several inland sites in Germany is combined with results from a recently developed approach of statistical back-trajectory analysis and additional data. Principal component analysis is then used to reveal the most important factors governing the abundance of DCAs in different particle size ranges. The two most important sources revealed are (i) photochemical formation during intense radiation days in polluted air masses, likely occurring in the gas phase on short timescales (gasSOA), and (ii) secondary reactions in anthropogenically influenced air masses, likely occurring in the aqueous phase on longer timescales (aqSOA). While the first source strongly impacts DCA concentrations mainly in small and large particles, the second one enhances accumulation mode DCAs and is responsible for the bulk of the observed concentrations. Primary sources were found to be minor (sea salt, soil resuspension) or non-existent (biomass burning, traffic). The results can be regarded as representative for typical central European continental conditions. © Author(s) 2014. Source

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