The radio structure of BL Lac object S5 2007+777

BL Lac object S5 2007+777 has been classified as a HYMOR (Hybrid Morphology radio source) for its hybrid FR I and FR II radio morphology. It is one of four BL Lac objects with a kpc scale extended X-ray jet. In this paper, we searched the unpublished European VLBI Network (EVN) archived high resolution data for this source, and present the high resolution radio structure. The EVN images all show a core-jet structure in 1.6, 5 and 8 GHz. In combination with the VLA data in the literature, we found position angle differences (ΔPA) of about 10°–20° between pc and kpc scale jet structures. The brightness temperature estimated from multi-band EVN images are around 10^11.2–10^11.8 K, from which the Doppler factor ranges from 3.2 to 12.0. We found significant flux variations of the radio core in 1.6 and 5 GHz, from which we derived the variability in brightness temperature T _var to be 10^13.6 K and 10^14.0 K, corresponding to the Doppler factors of 9.3 and 12.4, respectively.

     

Investigation on the thermo-mechanical properties and thermal stability of polylactic acid tissue engineering scaffold material

Thermogravimetric analysis and dynamic mechanical analysis were combined with scanning electron microscopy to analyze the thermo-mechanical properties and thermal stability of polylactic acid (PLA) foams fabricated using a solvent-free solid-state gas foaming method. The dependence of decomposition time and the lifetime on the PLA cell size was evaluated based on the thermal decomposition kinetic analyses. The results show that PLA specimens with larger cell sizes can be made at lower saturation gas pressures, which will ensure that the fabricated PLA foams have a shorter decomposition time, better flexibility, and are more satisfactory for medical requirements of tissue engineering scaffold (TES) material. The current work may help to optimize the PLA foaming parameters and precisely design PLA foams with different decomposition times according to specific TES requirements of different organ structures.     

Synchrotron peak luminosity,black hole mass and Eddington ratio for SDSS flat-spectrum radio quasars

For a sample of 185 flat-spectrum radio quasars (FSRQs) constructed from the SDSS DR3 quasar catalog, we found a significant correlation between the synchrotron peak luminosity and both the black hole mass and Eddington ratio. This implies that the physics of its jet formation is not only tightly related with the black hole mass, but also with the accretion rate. We verify that the synchrotron peak luminosity can be a better indicator of jet emission than 5 GHz luminosity, through comparing the relationships between each of these two parameters and both black hole mass and Eddington ratio. The fundamental plane of black hole activity for our FSRQs is established as L _r ∝ L ^0.80±0.06_x M ^{−0.04±0.09}_bh with a weak dependence on black hole mass, however, the scatter is significant.