Two-injection scenario for the hard X-ray excess observed in Mrk 421

An interesting result recently reported for Mrk 421 is the detection of a significant excess at hard X-ray energies, which could provide useful information for investigating particle acceleration and emission mechanisms in the relativistic jet. Considering a two-injection scenario, we develop a self-consistent one-zone leptonic model to understand the origin of the hard X-ray excess in Mrk 421 during the period of extremely low X-ray and very high energy (VHE) flux in 2013 January. In the model, two populations of mono-energetic ultrarelativistic electrons are injected into the emission region that is a magnetized plasmoid propagating along the blazar jet. We numerically calculate the emitting electron energy distribution by solving a kinetic equation that incorporates both shock acceleration and stochastic acceleration processes. Moreover, we infer analytic expressions relating electrons acceleration, cooling, escape and injection to the observed spectra and variability. For the injection luminosity in particular, we derive a new approximate analytical expression for the case of continual injection with a mono-energetic distribution. Based on a comparison between the theoretical predictions and the observed SED, we conclude that the hard X-ray excess observed in Mrk 421 may be due to the synchrotron radiation emitted by an additional electrons population, which is co-spatial with an electron population producing simultaneous Optical/UV, soft X-ray, and $\gamma$-ray emissions. The stochastic acceleration may play a major role in producing the observed X-ray spectrum.Comment: 12 pages, 4 figures, 2 tables, Accepted for publication in Ap

A γ\gamma-ray Quasi-Periodic modulation in the Blazar PKS 0301−-243?

We report a nominally high-confidence $\gamma$-ray quasi-periodic modulation in the blazar PKS 0301$-$243. For this target, we analyze its \emph{Fermi}-LAT Pass 8 data covering from 2008 August to 2017 May. Two techniques, i.e., the maximum likelihood optimization and the exposure-weighted aperture photometry, are used to build the $\gamma$-ray light curves. Then both the Lomb-Scargle Periodogram and the Weighted Wavelet Z-transform are applied to the light curves to search for period signals. A quasi-periodicity with a period of $2.1\pm0.3$ yr appears at the significance level of $\sim5\sigma$, although it should be noted that this putative quasi-period variability is seen in a data set barely four times longer. We speculate that this $\gamma$-ray quasi-periodic modulation might be evidence of a binary supermassive black hole.Comment: 9 pages, 8 figures; Accepted for publication in Ap

Voltammetric Behavior of o-Nitrophenol and Damage to DNA

The electrochemical behavior of o-nitrophenol was studied in detail with a glassy carbon electrode (GCE). The dependence of peak potential on pH indicated that equivalent electrons and protons were involved in the process of o-nitrophenol reduction. The interaction of o-nitrophenol with calf thymus DNA was investigated by adding DNA to the o-nitrophenol solution and by immobilizing DNA on GCE, respectively. The peak current decrement and peak potential shift in presence of DNA indicated that o-nitrophenol could interact with DNA. The result was demonstrated that the in situ DNA damage was detected by differential pulse voltammetry after the o-nitrophenol was electrochemically reduced

Optical and Gamma-Ray Variability Behaviors of 3C 454.3 from 2006 to 2011

We present our photometric monitoring of a flat spectrum radio quasar (FSRQ) 3C 454.3 at Yunnan observatories from 2006 to 2011. We find that the optical color of 3C 454.3 shows obvious redder-when-brighter trend, which reaches a saturation stage when the source is brighter than 15.15 mag at V band. We perform a simulation with multiple values of disk luminosity and spectral index to reproduce the magnitude-color diagram. The results show that the contamination caused by the disk radiation alone is difficult to produce the observed color variability. The variability properties during the outburst in December 2009 are also compared with $\gamma$-ray data derived from Fermi $\gamma$-ray space telescope. The flux variation of these two bands follow a linear relation with $F_{\gamma} \propto F_R^{1.14\pm0.07}$, which provides an observational evidence for external Compton process in 3C 454.3. Meanwhile, this flux correlation indicates that electron injection is the main mechanism for variability origin. We also explore the variation of the flux ratio $F_{\gamma}/F_R$ and the detailed structures in the lightcurves, and discuss some possible origins for the detailed variability behaviors.Comment: accepted for publication in The Astrophysical Journal, 5 figures, 2 table

Dissolution rate enhancement of repaglinide by solid dispersion

Purpose: To enhance the solubility and dissolution rate of the antidiabetic drug repaglinide by solid dispersion (SD) techniqueMethod: The solid dispersion of repaglinide was prepared by solvent evaporation method using the hydrophilic carrier,  polyethylene glycol 4000 (PEG 4000) in three drug:PEG 4000 ratios (1:1, 1:3, 1:5). For comparison, physical mixtures of repaglinide and PEG 4000 in the same ratios were also prepared. The formulations were characterized by Fourier transformed infrared spectroscopy (FTIR), x-ray diffractometry (XRD) and differential scanning colorimetry (DSC). Phase solubility study of pure repaglinide, physical mixture and solid dispersion was performed in distilled water. Dissolution studies were carried out in pH 7.4 phosphate buffer.Results: DSC and XRD results indicate that repaglinide exists in amorphous form in solid dispersion. FT-IR analysis demonstrated the presence of intermolecular hydrogen bonding between repaglinide and PEG 4000 in the solid dispersion. The solubility of pure repaglinide was enhanced from 22.5± 5.0 to 235.5± 5.0 μg/mL in distilled water at 37 0C. Rapid burst release (80 - 86 %) from the solid dispersion formulations was observed within 15 min.Conclusion: The solubility and dissolution rate of repaglinide are enhanced by formulating SDs of repaglinide with PEG 4000. This will likely lead to increase in bioavailability which would be beneficial for better glucose control in diabetic patients.Keywords: Diabetes, Solid dispersion, Repaglinide, Solubility, Dissolution, Burst releas

Histological and Molecular Characterization of Grape Early Ripening Bud Mutant

An early ripening bud mutant was analyzed based on the histological, SSR, and methylation-sensitive amplified polymorphism (MSAP) analysis and a layer-specific approach was used to investigate the differentiation between the bud mutant and its parent. The results showed that the thickness of leaf spongy tissue of mutant (MT) is larger than that of wild type (WT) and the differences are significant. The mean size of cell layer L2 was increased in the mutant and the difference is significant. The genetic background of bud mutant revealed by SSR analysis is highly uniform to its parent; just the variations from VVS2 SSR marker were detected in MT. The total methylation ratio of MT is lower than that of the corresponding WT. The outside methylation ratio in MT is much less than that in WT; the average inner methylation ratio in MT is larger than that in WT. The early ripening bud mutant has certain proportion demethylation in cell layer L2. All the results suggested that cell layer L2 of the early ripening bud mutant has changed from the WT. This study provided the basis for a better understanding of the characteristic features of the early ripening bud mutant in grape

N-Benzyl-2-propynamide

Pale-yellow crystals of the title compound, C10H9NO, have been obtained by the reaction of benzyl­amine and methyl propiolate. Weak inter­molecular hydrogen bonding is observed between acetyl­enic H and carbonyl O atoms. The crystal packing is stabilized by these C—H⋯O and by N—H⋯O inter­molecular hydrogen-bonding inter­actions