Three-dimensional super-resolution correlation-differential confocal microscopy with nanometer axial focusing accuracy

We present a correlation-differential confocal microscopy (CDCM), a novel method that can simultaneously improve the three-dimensional spatial resolution and axial focusing accuracy of confocal microscopy (CM). CDCM divides the CM imaging light path into two paths, where the detectors are before and after the focus with an equal axial offset in opposite directions. Then, the light intensity signals received from the two paths are processed by the correlation product and differential subtraction to improve the CM spatial resolution and axial focusing accuracy, respectively. Theoretical analyses and preliminary experiments indicate that, for the excitation wavelength of λ = 405 nm, numerical aperture of NA = 0.95, and the normalized axial offset of uM = 5.21, the CDCM resolution is improved by more than 20% and more than 30% in the lateral and axial directions, respectively, compared with that of the CM. Also, the axial focusing resolution important for the imaging of sample surface profiles is improved to 1 nm

(E)-2-Methyl-N-[4-(methyl­sulfon­yl)benzyl­idene]aniline

Mol­ecules of the title compound, C15H15NO2S, display an E configuration with respect to the C=N double bond. The crystal structure is stabilized by weak C—H⋯O hydrogen bonds. The dihedral angle between the two aromatic ring planes is 50.41 (12)°

(E,E)-N,N′-Bis[4-(methyl­sulfon­yl)benzyl­idene]ethane-1,2-diamine

In the crystal structure of the title Schiff base compound, C18H20N2O4S2, the mol­ecule lies across a crystallographic inversion centre. The torsion angle of the N—C—C—N fragment is 180°, as the inversion centre bis­ects the central C—C bond. The crystal packing is stabilized by C—H⋯O hydrogen bonds and aromatic π–π stacking inter­actions with a centroid–centroid distance of 3.913 (2) Å

4-(Methyl­sulfon­yl)benzaldehyde

In the crystal of the title compound, C8H8O3S, the mol­ecules are linked into a three-dimensional array by inter­molecular C—H⋯O hydrogen bonds

An Improved SNR Estimator for Wireless OFDM Systems

AbstractSNR is a crucial parameter for OFDM system and the assistant technology thereof such as Turbo coding, channel equalization. In this paper, we propose an improved SNR estimator which can be applied for the pilot structure in 3GPP standard. The modified second order moments of the pilot points after FFT are used to estimate noise variance in OFDM packets. The channel frequency responses of four subcarriers from adjacent two pilot points in distinct symbols could be used to inhibit the channel fading. Simulation results show that the proposed algorithm is robust to frequency selectivity and time selectivity in wireless channels, and its performance is considerably improved compared with the available methods