Studies of Copper (II) Complexes of Bioactive Peptides

Separation-based determinations of peptides hold the promise of measuring the concentrations of many peptides and their metabolites. However, typical chromatographic methods bear disadvantages in their selectivity and/or sensitivities. Thus, means for lowering detection limits are needed. The biuret reaction, the coordination of Cu(II) and peptides in basic solutions, provides a sensitive detection method based on the reversible Cu(III)/Cu(II) electrochemistry in peptide-bonded states.Thyrotropin-releasing hormone (TRH) is an important neuropeptide that undergoes the biuret reaction. The cationic form of TRH is not retained in a typical reversed-phase column. We have modified the common acidic mobile phase for peptide separation with a surfactant to retain the cationic TRH. A surfactant-preconditioned packed-bed capillary serves as the sample loop to preconcentrate TRH through sequential loading. The preconcentration has improved the detection limit for TRH 50-fold in the capillary HPLC-EC system. TRH lacks the N-terminal amine and C-terminal carboxylate that are usually required in the biuret reactions of Cu(II) and tripeptides. The unique structure of TRH affects the electrochemical behavior of the complex. We have utilized various electrochemical and spectroscopic techniques to determine the stoichiometry of the complex and to identify the binding sites in the peptide. Our data reveal that the interactions between Cu(II) and TRH are also possible under physiological pH. The unusual structure of TRH complicates the electrochemistry of Cu(II)-TRH complex. Multiple chemical reactions accompany the redox processes. We have investigated the kinetics of the coupling reactions using a rotating ring-disk electrode. The results suggest deprotonation of the ligand and inter-molecular interactions between complexes. Using microelectrode voltammetry, we have discovered that the octarepeat peptide of the prion protein is involved in Cu(II)/Cu(I) electrochemistry at physiological pH. This observation is relevant to the copper toxicity: Cu(II) may be reduced in vivo to Cu(I), which reacts with hydrogen peroxide to produce damaging oxidative radicals. The octarepeat peptide stabilizes Cu(I) by altering its redox potentials. Thus, the prion protein may have a function of anti-copper-toxicity

Convergence of wavelet thresholding estimators of differential operators

AbstractWavelet shrinkage is a strategy to obtain a nonlinear approximation to a given signal. The shrinkage method is applied in different areas, including data compression, signal processing and statistics. The almost everywhere convergence of resulting wavelet series has been established in [T. Tao, On the almost everywhere convergence of wavelet summation methods, Appl. Comput. Harmon. Anal. 3 (1996) 384–387] and [T. Tao, B. Vidakovic, Almost everywhere behavior of general wavelet shrinkage operators, Appl. Comput. Harmon. Anal. 9 (2000) 72–82]. With a representation of f′ in terms of wavelet coefficients of f, we are interested in considering the influence of wavelet thresholding to f on its derivative f′. In this paper, for the representation of differential operators in nonstandard form, we establish the almost everywhere convergence of estimators as threshold tends to zero

A survey on cyber security of CAV

With the ever fast developments of technologies in science and engineering, it is believed that CAV (connected and autonomous vehicles) will come into our daily life soon. CAV could be used in many different aspects in our lives such as public transportation and agriculture, and so on. Although CAV will bring huge benefits to our lives and society, issues such as cyber security threats, which may reveal drivers’ private information or even pose threat to driver’s life, present significant challenges before CAV can be utilised in our society. In computer science, there is a clear category of cyber security attacks while there is no specific survey on cyber security of CAV. This paper overviews different passive and active cyber security attacks which may be faced by CAV. We also present solutions of each of these attacks based on the current state-of-the-art, and discuss future improvements in research on CAV cyber security

Phase diagram and exotic spin-spin correlations of anisotropic Ising model on the Sierpi\'nski gasket

The anisotropic antiferromagnetic Ising model on the fractal Sierpi\'{n}ski gasket is intensively studied, and a number of exotic properties are disclosed. The ground state phase diagram in the plane of magnetic field-interaction of the system is obtained. The thermodynamic properties of the three plateau phases are probed by exploring the temperature-dependence of magnetization, specific heat, susceptibility and spin-spin correlations. No phase transitions are observed in this model. In the absence of a magnetic field, the unusual temperature dependence of the spin correlation length is obtained with $0 \leq$J$_b/$J$_a<1$, and an interesting crossover behavior between different phases at J$_b/$J$_a=1$ is unveiled, whose dynamics can be described by the J$_b/$J$_a$-dependence of the specific heat, susceptibility and spin correlation functions. The exotic spin-spin correlation patterns that share the same special rotational symmetry as that of the Sierpi\'{n}ski gasket are obtained in both the $1/3$ plateau disordered phase and the $5/9$ plateau partially ordered ferrimagnetic phase. Moreover, a quantum scheme is formulated to study the thermodynamics of the fractal Sierpi\'{n}ski gasket with Heisenberg interactions. We find that the unusual temperature dependence of the correlation length remains intact in a small quantum fluctuation.Comment: 9 pages, 12 figure

Towards a Severity Assessment Method for Potential Cyber Attacks to Connected and Autonomous Vehicles

CAV (connected and autonomous vehicle) is a crucial part of intelligent transportation systems. CAVs utilize both sensors and communication components to make driving decisions. A large number of companies, research organizations, and governments have researched extensively on the development of CAVs. The increasing number of autonomous and connected functions however means that CAVs are exposed to more cyber security vulnerabilities. Unlike computer cyber security attacks, cyber attacks to CAVs could lead to not only information leakage but also physical damage. According to the UK CAV Cyber Security Principles, preventing CAVs from cyber security attacks need to be considered at the beginning of CAV development. In this paper, a large set of potential cyber attacks are collected and investigated from the aspects of target assets, risks, and consequences. Severity of each type of attacks is then analysed based on clearly defined new set of criteria. The levels of severity for the attacks can be categorized as critical, important, moderate, and minor. Mitigation methods including prevention, reduction, transference, acceptance, and contingency are then suggested. It is found that remote control, fake vision on cameras, hidden objects to LiDAR and Radar, spoofing attack to GNSS, and fake identity in cloud authority are the most dangerous and of the highest vulnerabilities in CAV cyber security