Preparation of arylphosphinic acid derivatives as building blocks for binding sites

Several members of a new class of potential binding sites have been designed and prepared from a novel bis amino acid, bisphenylalanylphosphinic acid. The synthesis starts by making 4-iodophenylalanine, for which a greatly improved preparation has been developed. With this method, multi-gram quantities of 4-iodo-(S)-phenylalanine can be obtained easily in one step without racemization. The synthesis of bisphenylalanyl phosphinates, building blocks for binding sites, is an important part in the binding site synthesis. A simple and effective preparation of methyl ester of monoarylphosphinic acids has been developed, which involves palladium catalyzed coupling of aryl iodides with methyl phosphinate. This procedure is compatible with various functional groups and proceeds in reasonable yields. Symmetrically substituted diarylphosphinates can be prepared using two equivalents of the aryl iodide. Unsymmetrically substituted diarylphosphinates are readily obtained from the monoarylphosphinates derived from methyl phosphinate. Deprotection of the bisphenylalanylphosphinate and mixing it with a metal ion lead to self-assembled cyclic metal complex of bisphenylalanyl phosphinic acid. Selective deprotection and peptide coupling of bisphenylalanylphosphinate generate a dipeptide or a macrocyclic peptide. This macrocycle has a non-polar cavity, a hydrophilic external surface and multiple functional groups. The new method for making arylphosphinates also provides a general pathway for synthesis of inhibitors of tyrosine phosphatase;In connection with this research on molecular recognition, we developed an assay for rapidly screening many molecules for binding to a specific ligand. This assay is a novel application of two-dimensional thin layer chromatography

Combat Network Synchronization of UCAV Formation Based on RTBA Model

The paper aims at developing an efficient method to acquire a proper UCAV formation structure with robust and synchronized features. Here we introduce the RTBA (Route Temporary Blindness Avoidance) model to keep the structure stable and the HPSO (hybrid particle swarm optimization) method is given to find an optimal synchronized formation. The major contributions include the following: (1) setting up the dynamic hierarchy topologic structure of UCAV formation; (2) the RTB phenomenon is described and the RTBA model is put forward; (3) the node choosing rules are used to keep the invulnerability of the formation and the detective information quantifying method is given to measure the effectiveness of the connected nodes; and (4) the hybrid particle swarm optimization method is given to find an optimal synchronized topologic structure. According to the related principles and models, the simulations are given in the end, and the results show that the simplification of the model is available in engineering, and the RTBA model is useful to solve the real problems in combat in some degree

A Study of Radio Knots within Supernova Remnant Cassiopeia A

The study on the dynamic evolution of young supernova remnants (SNRs) is an important way to understand the density structure of the progenitor's circumstellar medium. We have reported the acceleration or deceleration, proper motion and brightness changes of 260 compact radio features in the second youngest known SNR Cas A at 5\,GHz based on the VLA data of five epochs from 1987 to 2004. The radio expansion center locates at $\alpha(1950)=23^{\rm h}21^{\rm m}9^{\rm s}_{\cdot}7 \pm 0^{\rm s}_{\cdot}29, \delta(1950)=+58^{\circ}32^{\prime}25^{\prime\prime}_{\cdot}2 \pm 2^{\prime\prime}_{\cdot}2$. Three-quarters of the compact knots are decelerating, this suggests that there are significant density fluctuations in the stellar winds of the remnant's progenitor. We have verified that the acceleration or deceleration of compact knots are not related with the distribution of brightness. The brightening, fading, disappearing or new appearing of compact radio features in Cas A suggests that the magnetic field in the remnant is changing rapidly.Comment: 20 pages,9 figures, ApJ accepte

Parameter Selection and Uncertainty Measurement for Variable Precision Probabilistic Rough Set

In this paper, we consider the problem of parameter selection and uncertainty measurement for a variable precision probabilistic rough set. Firstly, within the framework of the variable precision probabilistic rough set model, the relative discernibility of a variable precision rough set in probabilistic approximation space is discussed, and the conditions that make precision parameters α discernible in a variable precision probabilistic rough set are put forward. Concurrently, we consider the lack of predictability of precision parameters in a variable precision probabilistic rough set, and we propose a systematic threshold selection method based on relative discernibility of sets, using the concept of relative discernibility in probabilistic approximation space. Furthermore, a numerical example is applied to test the validity of the proposed method in this paper. Secondly, we discuss the problem of uncertainty measurement for the variable precision probabilistic rough set. The concept of classical fuzzy entropy is introduced into probabilistic approximation space, and the uncertain information that comes from approximation space and the approximated objects is fully considered. Then, an axiomatic approach is established for uncertainty measurement in a variable precision probabilistic rough set, and several related interesting properties are also discussed. Thirdly, we study the attribute reduction for the variable precision probabilistic rough set. The definition of reduction and its characteristic theorems are given for the variable precision probabilistic rough set. The main contribution of this paper is twofold. One is to propose a method of parameter selection for a variable precision probabilistic rough set. Another is to present a new approach to measurement uncertainty and the method of attribute reduction for a variable precision probabilistic rough set

Driving green bond market through energy prices, gold prices and green energy stocks: evidence from a nonlinear approach

One of the most controversial concerns among the researchers is the expansion of the green bond markets, so as to reduce environmental pollution. The present study estimates the factors that help drive the global green bond markets, such as energy prices, gold prices, and green energy stocks. The study has applied Quantile Autoregressive Lagged Approach (QARDL) and Quantile Granger Causality test to estimate the causal relationship among the variables for January 2010 and June 2021. The QARDL findings reveal that for all the quantiles, the error correction term is statistically significant with the predicted negative sign. This confirms the existence of a strong long-run equilibrium relationship between the relevant variables and the green bonds market on a global level. The findings revealed that gold and energy prices have a lower effect on the green bonds market on every quantile, and also from the low to medium quantiles, respectively. While at the same time, the green energy stocks have an increasing effect on the green bonds market at higher quantiles. The results of the causal examination using Granger-causality in quantiles show a bi-directional causal relationship between the green bonds, energy prices, gold prices, and green energy stocks in the world econom

Delay-Doppler Reversal for OTFS System in Doubly-selective Fading Channels

The recent proposed orthogonal time frequency space (OTFS) modulation shows signifcant advantages than conventional orthogonal frequency division multiplexing (OFDM) for high mobility wireless communications. However, a challenging problem is the development of effcient receivers for practical OTFS systems with low complexity. In this paper, we propose a novel delay-Doppler reversal (DDR) technology for OTFS system with desired performance and low complexity. We present the DDR technology from a perspective of two-dimensional cascaded channel model, analyze its computational complexity and also analyze its performance gain compared to the direct processing (DP) receiver without DDR. Simulation results demonstrate that our proposed DDR receiver outperforms traditional receivers in doubly-selective fading channels