Glutathione (GSH) conjugates with dopamine (DA)-derived quinones to form reactive or non-reactive GSH-conjugates

In this study we demonstrate for the first time that GSH could rapidly conjugate with dopamine (DA)-derived DA-o-quinones without enzymatic catalysis to form short-lived intermediate GSH-conjugates (2-S-GSH-DA-o-quinone and 5-S-GSH-DA-o-quinone). These intermediate GSH-conjugates are unstable and would finally form reactive or non-reactive GSH-conjugates dependent on ambient reductive forces. Under insufficient reductive forces, the intermediate GSH-conjugates could cyclize spontaneously to form reactive 7-S-GSH-aminochrome (7-S-GSH-AM). The 7-S-GSH-AM is so reactive that it could further react with another GSH to form 4,7-bi-GSH-5,6-dihydroindole. Its reactivity could also abrogate tyrosinase activity in solutions. In addition, the 7-S-GSH-AM could further undergo internal rearrangement to form non-reactive 7-S-GSH-5,6-dihydroindole. From these novel findings, we propose two detrimental positive feedback loops involving accelerated DA oxidation, increased GSH consumption and impaired GSH detoxification efficiency, as the underlying chemical explanation for dopaminergic neuron degeneration in Parkinson's disease

Halos in medium-heavy and heavy nuclei with covariant density functional theory in continuum

The covariant density functional theory with a few number of parameters has been widely used to describe the ground-state and excited-state properties for the nuclei all over the nuclear chart. In order to describe exotic properties of unstable nuclei, the contribution of the continuum and its coupling with bound states should be treated properly. In this Topical Review, the development of the covariant density functional theory in continuum will be introduced, including the relativistic continuum Hartree-Bogoliubov theory, the relativistic Hartree-Fock-Bogoliubov theory in continuum, and the deformed relativistic Hartree-Bogoliubov theory in continuum. Then the descriptions and predictions of the neutron halo phenomena in both spherical and deformed nuclei will be reviewed. The diffuseness of the nuclear potentials, nuclear shapes and density distributions, and the impact of the pairing correlations on nuclear size will be discussed.Comment: 63 pages; Topical Review, J. Phys. G (in press

The relativistic continuum Hartree-Bogoliubov description of charge-changing cross section for C,N,O and F isotopes

The ground state properties including radii, density distribution and one neutron separation energy for C, N, O and F isotopes up to the neutron drip line are systematically studied by the fully self-consistent microscopic Relativistic Continuum Hartree-Bogoliubov (RCHB) theory. With the proton density distribution thus obtained, the charge-changing cross sections for C, N, O and F isotopes are calculated using the Glauber model. Good agreement with the data has been achieved. The charge changing cross sections change only slightly with the neutron number except for proton-rich nuclei. Similar trends of variations of proton radii and of charge changing cross sections for each isotope chain is observed which implies that the proton density plays important role in determining the charge-changing cross sections.Comment: 10 pages, 4 figure

Solving the undirected feedback vertex set problem by local search

An undirected graph consists of a set of vertices and a set of undirected edges between vertices. Such a graph may contain an abundant number of cycles, then a feedback vertex set (FVS) is a set of vertices intersecting with each of these cycles. Constructing a FVS of cardinality approaching the global minimum value is a optimization problem in the nondeterministic polynomial-complete complexity class, therefore it might be extremely difficult for some large graph instances. In this paper we develop a simulated annealing local search algorithm for the undirected FVS problem. By defining an order for the vertices outside the FVS, we replace the global cycle constraints by a set of local vertex constraints on this order. Under these local constraints the cardinality of the focal FVS is then gradually reduced by the simulated annealing dynamical process. We test this heuristic algorithm on large instances of Er\"odos-Renyi random graph and regular random graph, and find that this algorithm is comparable in performance to the belief propagation-guided decimation algorithm.Comment: 6 page

Itinerant and localized magnetism on the triangular lattice: sodium rich phases of Nax_xCoO2_2

We study the interplay between correlation, itinerant ferromagnetism and local moment formation on the electron doped triangular lattice of sodium cobaltates Na$_x$CoO$_2$. We find that strong correlation renormalizes the Stoner criterion and stabilizes the paramagnetic state for $x<x_c\simeq0.67$. For $x>x_c$, ferromagnetic (FM) order emerges. The enhanced Na dopant potential fluctuations play a crucial role in the sodium rich phases and lead to an inhomogeneous FM state, exhibiting nonmagnetic Co$^{3+}$ patches, antiferromagnetic (AF) correlated regions, and FM clusters with AF domains. Hole doping the band insulator at x=1 leads to the formation of local moments near the Na vacancies and AF correlated magnetic clusters. We explain recent observations by neutron, $\mu$SR, and NMR experiments on the evolution of the magnetic properties in the sodium rich phases.Comment: revtex4 file, 5 pages, 3 figures, published versio

Modulation efficiency of LiNbO₃ waveguide electro-optic intensity modulator operating at high microwave frequency

The modulation efficiency, at high-frequency microwave modulation, of a LiNbO3 waveguide electro-optic modulator is shown to be degraded severely, especially when it is used as a frequency translator in a Brillouin-distributed fiber-sensing system. We derive an analytical expression for this attenuation regarding the phase-velocity mismatch and the impedance mismatch during the modulation process. Theoretical results are confirmed by experimental results based on a 15 Gb/s LiNbO3 optical intensity modulator