Electronic structure and superconductivity of BiS2-based compounds LaO1-xFxBiS2

Using the density-functional perturbation theory with structural optimization, we investigate the electronic structure, phonon spectra, and superconductivity of BiS2-based layered compounds LaO1-xFxBiS2. For LaO0.5F0.5BiS2, the calculated electron-phonon coupling constant is equal to lambda = 0.8, and obtained Tc = 9.1 K is very close to its experimental value, indicating that it is a conventional electron-phonon superconductor

Studies on Agrobacterium-mediated genetic transformation of embryogenic suspension cultures of sweet potato

In this study, genetic transformation of embryogenic suspension cultures of sweet potato (Ipomoea batatas) cultivar Xu55-2 was conducted utilizing the Agrobacterium tumefaciens strain EHA105 thatcontains the binary vector pBIN19/SBD2 with SBD2 (starch binding domain 2) gene and neomycin phosphotransferase (NPT II) gene. The presence of the SBD2 gene in the genomic DNA of transgenicplants was verified by PCR amplification and confirmed by Southern blot analysis. Results suggested that cefotaxime (Cefo), at the concentration of 200 mg/L, was able to effectively suppress the growth ofAgrobacterium after co-cultivation. The optimal concentration for kanamycin (Kan) was 10 mg/L for selecting resistance calli, somatic embryo formation and plant regeneration. The highest frequency ofshoot induction (30.9%) was obtained on the MS medium containing 10 mg/L Kan, 200 mg/L Cefo, 1.0 mg/L abscisic acid (ABA) and 1.0 mg/L gibberellic acid (GA3)

Limits from Weak Gravity Conjecture on Dark Energy Models

The weak gravity conjecture has been proposed as a criterion to distinguish the landscape from the swampland in string theory. As an application in cosmology of this conjecture, we use it to impose theoretical constraint on parameters of two types of dark energy models. Our analysis indicates that the Chaplygin-gas-type models realized in quintessence field are in the swampland, whereas the $a$ power-low decay model of the variable cosmological constant can be viable but the parameters are tightly constrained by the conjecture.Comment: Revtex4, 8 pages, 5 figures; References, minor corrections in content, and acknowledgement adde