Noble gas-transition metal complexes: coordination of ScO+ by multiple Ar, Kr, and Xe atoms in noble gas matrixes

The combination of matrix isolation infrared spectroscopic and density functional calculation results provides strong evidence that the transition metal monoxide cation, ScO+, coordinates five noble gas atoms in forming the [ScO(Ng)5]+ (Ng = Ar, Kr, or Xe) complexes in noble gas matrixes.     

Fringe pattern analysis by S-transform

S-transform proposed in 1996 by Stockwell R.G is a simple and popular technique for the time–frequency analysis. It has been introduced in optical three-dimensional shape measurement, recently. In this paper, a study about applications of S-transform in the demodulation of deformed fringe patterns is performed. We focus on discussing not only the S-transform spectrum filtering technique, the S-transform ridge technique and the phase gradient calculation method based on S-transform used in fringe pattern demodulation, but also the phase unwrapping technique. In addition, a generalized S-transform was introduced to analyze fringe patterns, which is helpful to improve the measurement accuracy and flexibility of the method based on S-transform. The reconstruction results based on S-transform were compared with that on wavelet transform and windowed Fourier transform in fringe analysis.     

S变换轮廓术中消除条纹非线性影响的方法

S变换是短时傅里叶变换和小波变换的延伸和推广,是一种无损可逆的非平稳信号时频分析方法.它不仅具有线性、多分辨性和逆变换唯一性等特点,而且其反变换与傅里叶变换保持着直接的联系.在S变换中,以简谐波作为基波,以可以同时进行伸缩和平移的高斯函数作为窗函数.同短时傅里叶变换相比,S变换的时频分辨率可以同时达到最佳,同小波变换相...     

Spatial-based iterative learning control for motion control applications

For many motion control applications spatial constraints are often more important than temporal constraints. In recent work, we have developed a spatial control strategy called the ε-controller for mobile robot applications. The control strategy is based solely on static path geometry with position (in space) feedback. Motivated by this idea, in this paper, we consider the notion of spatial-based iterative learning control (ILC). Specifically, we consider repetitive operation problems where corrections are made to the control signal from trial to trial. Unlike traditional ILC, however, which updates control signals based on the time elapsed along a trajectory, we instead make updates based on path errors and progress along the path. The idea is demonstrated via simulation for a system with bang–bang velocity control. Experimental results using a high-precision, two-axis gimbal mechanism are presented to show the effectiveness of the strategy.     

Noble gas-transition-metal complexes: coordination of VO2 and VO4 by Ar and Xe atoms in solid noble gas matrixes

The matrix isolation infrared spectroscopic and quantum chemical calculation results indicate that vanadium oxides, VO2 and VO4, coordinate noble gas atoms in forming noble gas complexes. The results showed that VO2 coordinates two Ar or Xe atoms and that VO4 coordinates one Ar or Xe atom in solid noble gas matrixes. Hence, the VO2 and VO4 molecules trapped in solid noble gas matrixes should be regarded as the VO2(Ng)2 and VO4(Ng) (Ng = Ar or Xe) complexes. The total V-Ng binding energies were predicted to be 12.8, 18.2, 5.0, and 7.3 kcal/mol, respectively, for the VO2(Ar)2, VO2(Xe)2, VO4(Ar), and VO4(Xe) complexes at the CCSD(T)//B3LYP level of theory.     

Observation of Spontaneous C=C Bond Breaking in the Reaction between Atomic Boron and Ethylene in Solid Neon

A ground‐state boron atom inserts into the C=C bond of ethylene to spontaneously form the allene‐like compound H₂CBCH₂ on annealing in solid neon. This compound can further isomerize to the propyne‐like HCBCH₃ isomer under UV light excitation. The observation of this unique spontaneous C=C bond insertion reaction is consistent with theoretical predictions that the reaction is thermodynamically exothermic and kinetically facile. This work demonstrates that the stronger C=C bond, rather than the less inert C?H bond, can be broken to form organoboron species from the reaction of a boron atom with ethylene even at cryogenic temperatures.     

Pentavalent Lanthanide Compounds: Formation and Characterization of Praseodymium(V) Oxides

The chemistry of lanthanides (Ln=La–Lu) is dominated by the low‐valent +3 or +2 oxidation state because of the chemical inertness of the valence 4f electrons. The highest known oxidation state of the whole lanthanide series is +4 for Ce, Pr, Nd, Tb, and Dy. We report the formation of the lanthanide oxide species PrO₄ and PrO₂⁺ complexes in the gas phase and in a solid noble‐gas matrix. Combined infrared spectroscopic and advanced quantum chemistry studies show that these species have the unprecedented Pr^V oxidation state, thus demonstrating that the pentavalent state is viable for lanthanide elements in a suitable coordination environment.     

Multiprotein Dynamic Combinatorial Chemistry: A Strategy for the Simultaneous Discovery of Subfamily‐Selective Inhibitors for Nucleic Acid Demethylases FTO and ALKBH3

Dynamic combinatorial chemistry (DCC) is a powerful supramolecular approach for discovering ligands for biomolecules. To date, most, if not all, biologically templated DCC systems employ only a single biomolecule to direct the self‐assembly process. To expand the scope of DCC, herein, a novel multiprotein DCC strategy has been developed that combines the discriminatory power of a zwitterionic “thermal tag” with the sensitivity of differential scanning fluorimetry. This strategy is highly sensitive and could differentiate the binding of ligands to structurally similar subfamily members. Through this strategy, it was possible to simultaneously identify subfamily‐selective probes against two clinically important epigenetic enzymes: FTO ( 7 ; IC₅₀=2.6 μm ) and ALKBH3 ( 8 ; IC₅₀=3.7 μm ). To date, this is the first report of a subfamily‐selective ALKBH3 inhibitor. The developed strategy could, in principle, be adapted to a broad range of proteins; thus it is of broad scientific interest.