Nondestructive Evaluation of Special Defects Based on Ultrasound Metasurface

We demonstrate the nondestructive evaluation by means of directional ultrasound emitted from a planar metasurface. The ultrasound metasurface is designed to generate the collimated and directional ultrasound efficiently in a planar configuration, which is endowed with the full-2π-range phase manipulation ability and high transmittance up to 80%. We employ the directional emission based on the ultrasound metasurface to innovate the traditional nondestructive evaluation methods, benefited from the freely controlled directivity and the superior fitness to sample surface of the planar metasurface. Merits of this innovative application are evidenced by the remarkable accuracy (higher than 98%) in the thickness evaluation, and precise detection (accuracy higher than 96%) of the special defect inside the V-shaped workpiece which is intractable to be inspected conventionally. The implementation of the metasurface-based directional ultrasound emission in the nondestructive evaluation bears the advantages of high coupling efficiency, superior fitness, high accuracy, and applicability to special defect, providing new solutions to the challenges in conventional defect detection and promotes the development in the nondestructive evaluation applications.

Ferroelectric Particles in Nematic Liquid Crystals with Soft Anchoring

A theoretical evaluation of the electric Freedericksz transition threshold and saturation field is proposed for a liquid crystals composite with ferroelectric particles. Existing models consider a strong anchoring of nematic molecules on the glass support of the cell, but in this paper a soft molecular anchoring of molecules on the glass support and also on the ferroelectric nanoparticle’s surface is assumed. Thus, a finite saturation field was obtained in agreement with real systems. Calculations are made for planar configuration of positive dielectric anisotropy liquid crystals. The results are compared with data obtained on similar systems from different publications and the differences are discussed.

Theoretical Studies on The Mechanism of Pd2+-Catalyzed Regioselective C-H Alkylation of Indole With MesICH2CF3OTf

The reaction mechanism of Pd2+-catalyzed regioselective C–H alkylation of indole with MesICH2CF3OTf has been investigated by the density functional theory calculations. The reaction mechanism mainly contains four steps：C-H activation, oxidative addition, reductive elimination and ligands substitution. From our calculations, we find that the C-H activation step was realized by the acetate anion (-OAc) assisted CMD process and the transition state of C-H activation process is a square planar configuration. Moreover, the calculation results suggest that the regioselectivity of C-H bond alkylation of indole with MesICH2CF3OTf can be ascribed to the different stability of the CMD transition states in C-H activation step and different acidities of C-H bonds.

A Nitrogen Doped Asymmetric Phenalenyl with Zwitterionic Ground State

Herein, an asymmetric N-doped phenalenyl compound (BTAP) was firstly synthesized and carefully studied. BTAP discloses a planar configuration and an unexpected zwitterionic ground state with the negative charge delocalized around...

Model of the broadband interferometric optical biosensor in a planar configuration

The paper presents numerical studies of the model of an optical sensor based on interference of modes in planar one-dimensional step-index configuration, excited by a broadband light source from a selected spectral range. The refractive index variation of measured external surrounding affects the modal properties of multimode waveguide and the spectral field distribution at the output of the structure. The optical system described is designed to the analysis of biological substances. Full Text: PDF ReferencesM. Blahut, "Optical sensor in planar configuration based on multimode interference" Proc. SPIE, 10455, (2017). CrossRef K. Misiakos, et al, "Broad-band Mach-Zehnder interferometers as high performance refractive index sensors: Theory and monolithic implementation", Opt. Express, 22, 8856, (2014). CrossRef K. Gut, "Study of a Broadband Difference Interferometer Based on Low-Cost Polymer Slab Waveguides", Nanomaterials, 9, 729 (2019). CrossRef M. Nordstrom, et al, "Single-Mode Waveguides With SU-8 Polymer Core and Cladding for MOEMS Applications", J. Light. Techn., 25, 1284, (2007). CrossRef D. Segelstein, "The complex refractive index of water", M.S. Thesis, University of Missouri, (1981). DirectLink https://www.yokogawa.com/pl/solutions/products-platforms/ DirectLink

Stereochemistry of Pt(η2-P2L)Cl2 derivatives

The coordination chemistry of platinum (Pt) covers a huge field as shown by a recent survey covering the crystallographic and structural data of almost 200 monomeric examples of the Pt(η2-P2L)Cl2 type. About 20% of these complexes exist as isomers and are discussed in this review. Included are distortion (64%), cis-trans (20%), and ligand (16%) isomers. These are discussed in terms of the metallocyclic rings, and coordinations are drawn between donor atoms, bond lengths, and interbond angles, with attention to any trans-influence. Distortion isomers, differing only by the degree of distortion in Pt-L and L-Pt-L angles, are the most numerous. In this series of distortion and ligand isomers, the square-planar configuration about the Pt(II) atom has only cis-configuration. The total mean values of Pt-L bond distances (cis- vs. trans-configuration) are 2.228 Å (P) and 2.353 Å (Cl) vs. 2.312 (P) and 2.302 Å (Cl).