Effect of hydrogen adsorption on the quasiparticle spectra of graphene

We use the non-interacting tight-binding model to study the effect of isolated hydrogen adsorbates on the quasiparticle spectra of single-layer graphene. Using the Green's function approach, we obtain analytic expressions for the local density of states and the spectral function of hydrogen-doped graphene, which are also numerically evaluated and plotted. Our results are relevant for the interpretation of scanning tunneling microscopy and angle-resolved photoemission spectroscopy data of functionalized graphene.Comment: 4 pages, 3 figures, minor corrections to tex

Energy gap opening in submonolayer lithium on graphene: Local density functional and tight-binding calculations

The adsorption of an alkali-metal submonolayer on graphene occupying every third hexagon of the honeycomb lattice in a commensurate $(\sqrt{3}\times\sqrt{3})R30^\circ$ arrangement induces an energy gap in the spectrum of graphene. To exemplify this type of band gap, we present \textit{ab initio} density functional theory calculations of the electronic band structure of C$_6$Li. An examination of the lattice geometry of the compound system shows the possibility that the nearest-neighbor hopping amplitudes have alternating values constructed in a Kekul\'e-type structure. The band structure of the textured tight-binding model is calculated and shown to reproduce the expected band gap as well as other characteristic degeneracy removals in the spectrum of graphene induced by lithium adsorption. More generally we also deduce the possibility of energy gap opening in periodic metal on graphene compounds C$_x$M if $x$ is a multiple of 3.Comment: 7 pages, 5 figures, published versio

Comment on "Band structure engineering of graphene by strain: First-principles calculations"

In their first-principles calculations of the electronic band structure of graphene under uniaxial strain, Gui, Li, and Zhong [Phys. Rev. B \textbf{78}, 075435 (2008)] have found opening of band gaps at the Fermi level. This finding is in conflict with the tight-binding description of graphene which is closed gap for small strains. In this Comment, we present first-principles calculations which refute the claim that strain opens band gaps in graphene.Comment: published versio

Laboratory-based and office-based Globorisk scores to predict 10-year risk of cardiovascular diseases among Iranians: results from the Fasa PERSIAN cohort.

BACKGROUND: Globorisk is a novel risk prediction model for predicting cardiovascular disease (CVD). Globorisk is a country-specific risk prediction model that determines CVD risk for all countries. This model has two versions; laboratory-based and office-based. This study aimed to determine the agreement between laboratory-based and office-based models in a large sample of the general population. METHODS: Baseline data from the Fasa cohort study was used for the current study. In total, 6810 participants ≥ 40 years without any history of cardiovascular disease or stroke were included in the study. To determine the laboratory-based risk model, factors include age, sex, current smoking status, history of diabetes, systolic blood pressure (SBP), and total cholesterol. To estimate the office-based risk model, factors were age, sex, current smoking status, SBP, and body mass index (BMI). Kappa statistics was used to distinguish the agreement between grouped scores in these two models. Additionally, correlation coefficients and scatter plots were used to determine the linear correlation between the two models. RESULTS: In this study 46.53% of the participants were men. The mean age (SD) of participants was 51.08 (7.88) years. Agreements between the two models were moderate and substantial in all women and all men, respectively. The agreement between the two CVD risk groups was 90.15% (kappa = 0.717) in all men, 92.94% (kappa = 0.571) among men aged  60 years (r = 0.94). Among all women, there was a very strong positive correlation (r = 0.87), and the strong positive correlation remained among  60 years old (r = 0.76). CONCLUSION: The Globorisk office-based model which is easier to use as it does not require blood testing can determine the risk groups in this population. The Globorisk office-based model may be used for CVD risk screening in low-middle income countries where resources are limited

A risk-seeking future

The 2014 IPCC Assessment expresses doubt that the global surface temperature increase will remain within the 2 °C target without deploying risky carbon-capturing or solar radiation-deflecting technologies. New behavioural research suggests that, if the IPCC is right, citizens and policymakers will support such risk-taking

Inhibition of adrenal steroidogenesis and heat shock protein 70 induction in neonatally feed restricted broiler chickens under heat stress condition.

This study was conducted to determine the roles of plasma corticosterone concentration (CORT) and heat shock protein 70 (Hsp70) expression in the acquisition of thermotolerance in broiler chickens subjected to neonatal feed restriction.Equal numbers of chicks were divided into one of the four feeding regimens: ad libitum (control), 60% feed restriction on days 4, 5 and 6 (FR60), 60% feed restriction on days 4, 5 and 6 + 1500 mg/kg metyrapone (FR60M) and 60% feed restriction on days 4, 5 and 6 + 1500 mg/kg quercetin (FR60Q). From 35 to 42 days of age, all birds were exposed to 37 ± 1°C and 70-80% relative humidity for 3 h/day. The neonatal feed restriction elevated heterophil to lymphocyte ratios (HLR), CORT and Hsp70 expression in FR60 chicks. The FR60M and FR60Q treatments suppressed CORT and Hsp70 expression, respectively. Subjecting birds to FR60 improved feed conversion ratio (FCR) and body weight gain, and reduced HLR when compared to controls in response to heat exposure. Following heat exposure, the HLR and weight gain of FR60M and control birds were not significantly different. Although FR60Q chickens had improved FCR and weight gain, their HLR were similar to controls following heat exposure. The control birds had significantly lower CORT than other groups in response to heat exposure. The Hsp70 expression of FR60 and FR60Q birds was lower than those of control and FR60M groups. It is concluded that Hsp70 expression didnot appear to be a major indicator of thermotolerance acquisitionin neonataly manipulated broiler chickens

Strained graphene: tight-binding and density functional calculations

We determine the band structure of graphene under strain using density functional calculations. The ab-initio band strucure is then used to extract the best fit to the tight-binding hopping parameters used in a recent microscopic model of strained graphene. It is found that the hopping parameters may increase or decrease upon increasing strain, depending on the orientation of the applied stress. The fitted values are compared with an available parametrization for the dependence of the orbital overlap on the distance separating the two carbon atoms. It is also found that strain does not induce a gap in graphene, at least for deformations up to 10%

Bioactive calcium phosphate coatings applied to flexible poly(carbonate urethane) foils

Long-term fixation of orthopaedic implants can be enhanced by tissue ingrowth techniques. As such, the deposition of a bioactive bone-like coating could be considered a promising method to facilitate the integration of implants onto bone tissue. In this study, we identified the optimized osteo-conductive Calcium Phosphate (CaP) coating parameters for deposition on PolyCarbonate-Urethane (PCU) foils. The oxygen plasma surface-activated PCU specimens were suspended in simulated body fluid (SBF) and supersaturated SBFs for 4 h, 8 h, 24 h, or 6 days at a temperature of 20 °C, 37 °C, or 50 °C. This resulted in semi-crystalline CaP coatings on a thin flexible foil via a one-step low-temperature aqueous technique. The deposited CaP coatings demonstrated high stability and remained intact upon bending deformation. According to the in vitro cell assessments, the conducted CaP coatings did not influence cell viability nor cell proliferation compared to the bare PCU substrate. In addition, the deposited CaP coatings enhanced the cell-mediated calcium deposition. All in all, this paper demonstrates a promising method to apply stable bioactive coatings to flexible PCU foils, which can be a promising strategy for the enhanced integration of PCU implants onto bone.</p