Electron-capture supernovae exploding within their progenitor wind

The most massive stars on the asymptotic giant branch (AGB), so called super-AGB stars, are thought to produce supernovae (SNe) triggered by electron captures in their degenerate O+Ne+Mg cores. Super-AGB stars are expected to have slow winds with high mass-loss rates, so their wind density is high. The explosions of super-AGB stars are therefore presumed to occur in this dense wind. We provide the first synthetic light curves (LCs) for such events by exploding realistic electron-capture supernova (ecSN) progenitors within their super-AGB winds. We find that the early LC, i.e. before the recombination wave reaches the bottom of the H-rich envelope of SN ejecta (the plateau phase), is not affected by the dense wind. However, after the plateau phase, the luminosity remains higher when the super-AGB wind is taken into account. We compare our results to the historical LC of SN 1054, the progenitor of the Crab Nebula, and show that the explosion of an ecSN within an ordinary super-AGB wind can explain the LC features. We conclude that SN 1054 could have been a Type IIn SN without any extra extreme mass loss which was previously suggested to be necessary to account for its early high luminosity. We also show that our LCs match Type IIn SNe with an early plateau phase (`Type IIn-P') and suggest that they are ecSNe within super-AGB winds. Although some ecSNe can be bright in the optical spectral range due to the large progenitor radius, their X-ray luminosity from the interaction does not necessarily get as bright as other Type IIn SNe whose optical luminosities are also powered by the interaction. Thus, we suggest that optically-bright X-ray-faint Type IIn SNe can emerge from ecSNe. Optically-faint Type IIn SNe, such as SN 2008S, can also originate from ecSNe if their H-rich envelope masses are small. Some of them can be observed as `Type IIn-b' SNe due to the small H-rich envelope mass.Comment: 8 pages, 6 figures, accepted by Astronomy & Astrophysics, abstract abridge

Supernovae from Red Supergiants with Extensive Mass Loss

We calculate multicolor light curves (LCs) of supernovae (SNe) from red supergiants (RSGs) exploded within dense circumstellar medium (CSM). Multicolor LCs are calculated by using a multi-group radiation hydrodynamics code STELLA. If CSM is dense enough, the shock breakout signal is delayed and smeared by CSM and kinetic energy of SN ejecta is efficiently converted to thermal energy which is eventually released as radiation. We find that explosions of RSGs are affected by CSM in early epochs when mass-loss rate just before the explosions is higher than 10^{-4} Msun/yr. Their characteristic features are that the LC has a luminous round peak followed by a flat LC, that multicolor LCs are simultaneously bright in ultraviolet and optical at the peak, and that photospheric velocity is very low at these epochs. We calculate LCs for various CSM conditions and explosion properties, i.e., mass-loss rates, radii of CSM, density slopes of CSM, explosion energies of SN ejecta, and SN progenitors inside, to see their influence on LCs. We compare our model LCs to those of ultraviolet-bright Type IIP SN 2009kf and show that the mass-loss rate of the progenitor of SN 2009kf just before the explosion is likely to be higher than 10^{-4} Msun/yr. Combined with the fact that SN 2009kf is likely to be an energetic explosion and has large 56Ni production, which implies that the progenitor of SN 2009kf is a massive RSG, our results indicate that there could be some mechanism to induce extensive mass loss in massive RSGs just before their explosions.Comment: 16 pages, 17 figures, 3 tables, accepted by Monthly Notices of the Royal Astronomical Society, the unit of Lbol in Table 3 corrected in v

Shock Breakout in Type II Plateau Supernovae: Prospects for High Redshift Supernova Surveys

Shock breakout is the brightest radiative phenomenon in a supernova (SN) but is difficult to be observed owing to the short duration and X-ray/ultraviolet (UV)-peaked spectra. After the first observation from the rising phase reported in 2008, its observability at high redshift is attracting enormous attention. We perform multigroup radiation hydrodynamics calculations of explosions for evolutionary presupernova models with various main-sequence masses $M_{\rm MS}$, metallicities $Z$, and explosion energies $E$. We present multicolor light curves of shock breakout in Type II plateau SNe, being the most frequent core-collapse SNe, and predict apparent multicolor light curves of shock breakout at various redshifts $z$. We derive the observable SN rate and reachable redshift as functions of filter $x$ and limiting magnitude $m_{x,{\rm lim}}$ by taking into account an initial mass function, cosmic star formation history, intergalactic absorption, and host galaxy extinction. We propose a realistic survey strategy optimized for shock breakout. For example, the $g'$-band observable SN rate for $m_{g',{\rm lim}}=27.5$ mag is 3.3 SNe degree$^{-2}$ day$^{-1}$ and a half of them locates at $z\geq1.2$. It is clear that the shock breakout is a beneficial clue to probe high-$z$ core-collapse SNe. We also establish ways to identify shock breakout and constrain SN properties from the observations of shock breakout, brightness, time scale, and color. We emphasize that the multicolor observations in blue optical bands with $\sim$ hour intervals, preferably over $\geq2$ continuous nights, are essential to efficiently detect, identify, and interpret shock breakout.Comment: 26 pages, 23 figures. Accepted for publication in the Astrophysical Journal Supplement Serie

Mucoadhesive chitosan-coated PLGA nanoparticles for oral delivery of ferulic acid

This paper describes the development and in vitro evaluation of poly(lactic-co-glycolic acid) (PLGA) nanoparticles coated with chitosan (CS) for oral delivery of ferulic acid (FA). Nanoparticles were obtained by an emulsion evaporation technique and characterized. Furthermore, we evaluated the scavenging activity over hypochlorous acid (HOCl), the cytotoxicity over tumour cells and the in vitro intestinal permeability. Nanoparticles were spherical with a mean diameter of 242 nm, positive zeta potential and 50% of encapsulation efficiency. The in vitro release in phosphate buffered saline (PBS) (pH 7.4) demonstrated a prolonged and biphasic profile diffusion-controlled. In simulated gastrointestinal fluids, about 15% of FA was released in gastric fluid and a negligible release was observed in the intestinal fluid. In the HOCl scavenging activity and cytotoxicity over B16-F10 and HeLa cells, FA-loaded nanoparticles presented the same efficacy of the free drug. Besides, in the antioxidant and cytotoxic assay, CS contributed to FA effects. In the intestinal permeability study, FA-loaded nanoparticles exhibited a permeation of 6% through the Caco-2 monolayer and 20% through the Caco-2/HT29-MTX/Raji B co-culture. CS-coated PLGA nanoparticles are promising carriers for oral delivery of FA.This study was supported by the CAPES (Coordenação de Aperfeiçoamento de Pessoal de Ńıvel Superior) in the form of doctoral fellowship for I.A. de Lima, Fundação Araucária (17/17) CNPq (Conselho Nacional de Desenvolvimento Científico e tecnológico) and Finep (Financiadora de Estudos and Projetos) for partial financial support

Mucoadhesive chitosan-coated PLGA nanoparticles for oral delivery of ferulic acid

This paper describes the development and in vitro evaluation of poly(lactic-co-glycolic acid) (PLGA) nanoparticles coated with chitosan (CS) for oral delivery of ferulic acid (FA). Nanoparticles were obtained by an emulsion evaporation technique and characterized. Furthermore, we evaluated the scavenging activity over hypochlorous acid (HOCl), the cytotoxicity over tumour cells and the in vitro intestinal permeability. Nanoparticles were spherical with a mean diameter of 242 nm, positive zeta potential and 50% of encapsulation efficiency. The in vitro release in phosphate buffered saline (PBS) (pH 7.4) demonstrated a prolonged and biphasic profile diffusion-controlled. In simulated gastrointestinal fluids, about 15% of FA was released in gastric fluid and a negligible release was observed in the intestinal fluid. In the HOCl scavenging activity and cytotoxicity over B16-F10 and HeLa cells, FA-loaded nanoparticles presented the same efficacy of the free drug. Besides, in the antioxidant and cytotoxic assay, CS contributed to FA effects. In the intestinal permeability study, FA-loaded nanoparticles exhibited a permeation of 6% through the Caco-2 monolayer and 20% through the Caco-2/HT29-MTX/Raji B co-culture. CS-coated PLGA nanoparticles are promising carriers for oral delivery of FA.This study was supported by the CAPES (Coordenação de Aperfeiçoamento de Pessoal de Ńıvel Superior) in the form of doctoral fellowship for I.A. de Lima, Fundação Araucária (17/17) CNPq (Conselho Nacional de Desenvolvimento Científico e tecnológico) and Finep (Financiadora de Estudos and Projetos) for partial financial support

B^0-\bar{B}^0 mixing with quenched lattice NRQCD

We present our recent results for the B-parameters, which parameterize the \Delta B=2 transition amplitudes. Calculations are made in quenched QCD at \beta=5.7, 5.9, and 6.1, using NRQCD for heavy quark and the $O(a)$-improved action for light quark. The operators are perturbatively renormalized including corrections of O(\alpha_s/am_Q). We examine scaling behavior of the B-parameters in detail, and discuss the systematic uncertainties using scatter of results with different analysis procedures adopted. As a result, we find B_{B_d}(m_b)=0.84(2)(8), B_{B_s}/B_{B_d}=1.017(10)(^{+4}_{-0}) and B_{S_s}(m_b)=0.87(1)(9)(^{+1}_{-0}) in the quenched approximation.Comment: Lattice 2000 (Heavy Quark Physics), 4 pages, 4 eps-figures, Latex, typo correcte

Heavy quark expansion parameters from lattice NRQCD

Using the lattice NRQCD action for heavy quark, we calculate the heavy quark expansion parameters $\mu_{\pi}^2$ and $\mu_G^2$ for heavy-light mesons and heavy-light-light baryons. The results are compared with the mass differences among heavy hadrons to test the validity of HQET relations on the lattice.Comment: Lattice2001(heavyquark), 3 pages, 4 figure