108,073 research outputs found
Heterodimerization of apelin receptor and neurotensin receptor 1 induces phosphorylation of ERK1/2 and cell proliferation via Gαq-mediated mechanism
Dimerization of G protein-coupled receptors (GPCRs) is crucial for receptor function including agonist affinity, efficacy, trafficking and specificity of signal transduction, including G protein coupling. Emerging data suggest that the cardiovascular system is the main target of apelin, which exerts an overall neuroprotective role, and is a positive regulator of angiotensin-converting enzyme 2 (ACE2) in heart failure. Moreover, ACE2 cleaves off C-terminal residues of vasoactive peptides including apelin-13, and neurotensin that activate the apelin receptor (APJ) and neurotensin receptor 1 (NTSR1) respectively, that belong to the A class of GPCRs. Therefore, based on the similar mode of modification by ACE2 at peptide level, the homology at amino acid level and the capability of forming dimers with other GPCRs, we have been suggested that APJ and NTSR1 can form a functional heterodimer. Using co-immunoprecipitation, BRET and FRET, we provided conclusive evidence of heterodimerization between APJ and NTSR1 in a constitutive and induced form. Upon agonist stimulation, hetrodimerization enhanced ERK1/2 activation and increased proliferation via activation of Gq α-subunits. These novel data provide evidence for a physiological role of APJ/NTSR1 heterodimers in terms of ERK1/2 activation and increased intracellular calcium and induced cell proliferation and provide potential new pharmaceutical targets for cardiovascular disease. © 2014 The Authors
Dynamics of Vibrated Granular Monolayers
We study statistical properties of vibrated granular monolayers using
molecular dynamics simulations. We show that at high excitation strengths, the
system is in a gas state, particle motion is isotropic, and the velocity
distributions are Gaussian. As the vibration strength is lowered the system's
dimensionality is reduced from three to two. Below a critical excitation
strength, a gas-cluster phase occurs, and the velocity distribution becomes
bimodal. In this phase, the system consists of clusters of immobile particles
arranged in close-packed hexagonal arrays, and gas particles whose energy
equals the first excited state of an isolated particle on a vibrated plate.Comment: 4 pages, 6 figs, revte
Non-adiabatic Fast Control of Mixed States based on Lewis-Riesenfeld Invariant
We apply the inversely-engineered control method based on Lewis-Riesenfeld
invariants to control mixed states of a two-level quantum system. We show that
the inversely-engineered control passages of mixed states - and pure states as
special cases - can be made significantly faster than the conventional
adiabatic control passages, which renders the method applicable to quantum
computation. We devise a new type of inversely-engineered control passages, to
be coined the antedated control passages, which further speed up the control
significantly. We also demonstrate that by carefully tuning the control
parameters, the inversely-engineered control passages can be optimized in terms
of speed and energy cost.Comment: 9 pages, 9 figures, version to appear in J. Phys. Soc. Jp
A Lattice Boltzmann method for simulations of liquid-vapor thermal flows
We present a novel lattice Boltzmann method that has a capability of
simulating thermodynamic multiphase flows. This approach is fully
thermodynamically consistent at the macroscopic level. Using this new method, a
liquid-vapor boiling process, including liquid-vapor formation and coalescence
together with a full coupling of temperature, is simulated for the first time.Comment: one gzipped tar file, 19 pages, 4 figure
Structure-Induced Reversible Anionic Redox Activity in Na Layered Oxide Cathode
Anionic redox reaction (ARR) in lithium- and sodium-ion batteries is under hot discussion, mainly regarding how oxygen anion participates and to what extent oxygen can be reversibly oxidized and reduced. Here, a P3-type Na0.6[Li0.2Mn0.8]O2 with reversible capacity from pure ARR was studied. The interlayer O-O distance (peroxo-like O-O dimer, 2.506(3) Å), associated with oxidization of oxygen anions, was directly detected by using a neutron total scattering technique. Different from Li2RuO3 or Li2IrO3 with strong metal-oxygen (M-O) bonding, for P3-type Na0.6[Li0.2Mn0.8]O2 with relatively weak Mn-O covalent bonding, crystal structure factors might play an even more important role in stabilizing the oxidized species, as both Li and Mn ions are immobile in the structure and thus may inhibit the irreversible transformation of the oxidized species to O2 gas. Utilization of anionic redox reaction (ARR) on oxygen has been considered as an effective way to promote the charge-discharge capacity of the layered oxide cathodes for lithium- or sodium-ion batteries. The detailed mechanism of ARR, in particular how crystal structure affects and coordinates with the ARR, is not yet well understood. In the present work, a combination of X-ray and neutron total scattering measurements has been performed to study the structure of the prototype P3-type layered Na0.6[Li0.2Mn0.8]O2 with pure ARR. Unique structural characteristics, rather than prevailing knowledge of covalency of metal-oxygen, enable the stabilization of the crystal structure of Na0.6[Li0.2Mn0.8]O2 along with the ARR. This work suggests that reversible ARR can be manipulated by proper structure designs, thus to achieve high lithium or sodium storage in layered oxide cathodes. For P3-type Na0.6[Li0.2Mn0.8]O2 with relatively weak Mn-O covalent bonding, crystal structure factors play an important role in stabilizing the oxidized species, inhibiting the irreversible transformation of the oxidized species to O2 gas. The finding is important for better design of layered oxide positive materials with higher reversible capacity via the introduction of a reversible anionic redox reaction
Mapping the magneto-structural quantum phases of Mn3O4
We present temperature-dependent x-ray diffraction and temperature- and
field-dependent Raman scattering studies of single crystal Mn3O4, which reveal
the novel magnetostructural phases that evolve in the spinels due to the
interplay between strong spin-orbital coupling, geometric frustration, and
applied magnetic field. We observe a structural transition from tetragonal to
monoclinic structures at the commensurate magnetic transition at T2=33K, show
that the onset and nature of this structural transition can be controlled with
an applied magnetic field, and find evidence for a field-tuned quantum phase
transition to a tetragonal incommensurate or spin glass phase.Comment: 5 pages, 3 figures, submitted to Phys. Rev. Lett; typos correcte
Evidance for an Oxygen Diffusion Model for the Electric Pulse Induced Resistance Change Effect in Oxides
Electric pulse induced resistance (EPIR) switching hysteresis loops for
Pr0.7Ca0.7MnO3 (PCMO) perovskite oxide films were found to exhibit an
additional sharp "shuttle peak" around the negative pulse maximum for films
deposited in an oxygen deficient ambient. The device resistance hysteresis loop
consists of stable high resistance and low resistance states, and transition
regions between them. The resistance relaxation of the "shuttle peak" and its
temperature behavior as well as the resistance relaxation in the transition
regions were studied, and indicate that the resistance switching relates to
oxygen diffusion with activation energy about 0.4eV. An oxygen diffusion model
with the oxygen ions (vacancies) as the active agent is proposed for the
non-volatile resistance switching effect in PCMO.Comment: 7 pages, 5 figure
Metamaterials: optical activity without chirality
We report that the classical phenomenon of optical activity, which is traditionally associated with chirality (helicity) of organic molecules, proteins, and inorganic structures, can be observed in artificial planar media which exhibit neither 3D nor 2D chirality. We observe the effect in the microwave and optical parts of the spectrum at oblique incidence to regular arrays of nonchiral subwavelength metamolecules in the form of strong circular dichroism and birefringence indistinguishable from those of chiral three-dimensional media
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