A tight binding and k.p study of monolayer stanene

Stanene is a single layer of tin atoms which has been discovered as an emerging material for quantum spin Hall related applications. In this paper, we present an accurate tight-binding model for single layer stanene near the Fermi level. We parameterized the onsite and hopping energies for the nearest, second nearest, and third nearest neighbor tight-binding method, both without and with spin orbital coupling. We derived the analytical solution for the →Γ and .→K points and numerically investigated the buckling effect on the material electronic properties. In these points of the reciprocal space, we also discuss a corresponding →k . →p description, obtaining the value of the →k . →p parameters both analytically from the tight-binding ones, and numerically, fitting the ab-initio dispersion relations. Our models provide a foundation for large scale atomistic device transport calculations

Time-Course Analysis of Gene Expression During the Saccharomyces cerevisiae Hypoxic Response

Many cells experience hypoxia, or low oxygen, and respond by dramatically altering gene expression. In the yeast Saccharomyces cerevisiae, genes that respond are required for many oxygen-dependent cellular processes, such as respiration, biosynthesis, and redox regulation. To more fully characterize the global response to hypoxia, we exposed yeast to hypoxic conditions, extracted RNA at different times, and performed RNA sequencing (RNA-seq) analysis. Time-course statistical analysis revealed hundreds of genes that changed expression by up to 550-fold. The genes responded with varying kinetics suggesting that multiple regulatory pathways are involved. We identified most known oxygen-regulated genes and also uncovered new regulated genes. Reverse transcription-quantitative PCR (RT-qPCR) analysis confirmed that the lysine methyltransferase EFM6 and the recombinase DMC1, both conserved in humans, are indeed oxygen-responsive. Looking more broadly, oxygen-regulated genes participate in expected processes like respiration and lipid metabolism, but also in unexpected processes like amino acid and vitamin metabolism. Using principle component analysis, we discovered that the hypoxic response largely occurs during the first 2 hr and then a new steady-state expression state is achieved. Moreover, we show that the oxygen-dependent genes are not part of the previously described environmental stress response (ESR) consisting of genes that respond to diverse types of stress. While hypoxia appears to cause a transient stress, the hypoxic response is mostly characterized by a transition to a new state of gene expression. In summary, our results reveal that hypoxia causes widespread and complex changes in gene expression to prepare the cell to function with little or no oxygen

Hyperfine Fields in an Ag/Fe Multilayer Film Investigated with 8Li beta-Detected Nuclear Magnetic Resonance

Low energy $\beta$-detected nuclear magnetic resonance ($\beta$-NMR) was used to investigate the spatial dependence of the hyperfine magnetic fields induced by Fe in the nonmagnetic Ag of an Au(40 \AA)/Ag(200 \AA)/Fe(140 \AA) (001) magnetic multilayer (MML) grown on GaAs. The resonance lineshape in the Ag layer shows dramatic broadening compared to intrinsic Ag. This broadening is attributed to large induced magnetic fields in this layer by the magnetic Fe layer. We find that the induced hyperfine field in the Ag follows a power law decay away from the Ag/Fe interface with power $-1.93(8)$, and a field extrapolated to $0.23(5)$ T at the interface.Comment: 5 pages, 4 figure. To be published in Phys. Rev.

Effects of Swertia chirata on some blood biochemical parameters in streptozotocin diabetic rats

The antidiabetic effect of aqueous and hexane extracts of Swertia chirata was studied in streptozotocininduced diabetic rats. Type II diabetes was induced by injecting streptozotocin (STZ) subcutaneously to adult (ten to twelve weeks old) mixed albino male (Long Evan's Strain) rats. Aqueous extracts of Swertia chirata at 75 and 125 mg/kg body wt. (AqSC75 and AqSC125), hexane extracts of Swertia chirata at 50 and 109 mg/kg body weight (HeSC50 and HeSC100) and glibenclamide at 600 pg/kg body wt. (an oral antidiabetic drug) were given orally for 16 days to STZ induced diabetic rats. In diabetic rats, all the different extracts as well as glibenclamide produced a significant (P<0.01) antihyperglycemic effect, the markedly higher being in the groups treated with HeSC50 and HeSCioo followed by AqSC125 and AqSC75. Both aqueous and hexane extracts of Swertia chirata exhibited anti-hypercholesterolernic effect in STZ diabetic rats. But glibenclamide had virtually no cholesterol lowering effect. All forms of extracts at different doses decreased serum TAG levels significantly (P<0.01) in diabetic rats; the highest decrease (60%) in TAG level was observed in animals of the group treated with HeSCioo. In STZ-rats, a fall in SGPT levels was observed in all the groups treated with different extracts and glibenclamide; the Most affected was the group treated with HeSC5o. On the other hand, an increase in SGOT level, another liver enzyme, was observed in groups treated with glibenclamide. But aqueous and hexane extracts of Swertia chirata decreased SGOT levels compared with diabetic control group. Thus the above observations suggest that extracts, from Swertia chirata possess antidiabetic principle and can presumably be used for the treatment of diabetes mellitus