42 research outputs found
Density functional and dynamics study of the dissociative adsorption of hydrogen on
a b s t r a c t A first principles study is performed to investigate the adsorption characteristics of hydrogen on magnesium surface. Substitutional and on-surface adsorption energies are calculated for Mg (0 0 0 1) surface alloyed with the selected elements. To further analyze the hydrogen-magnesium interaction, first principles molecular dynamics method is used which simulates the behavior of H 2 at the surface. Also, charge density differences of substitutionally doped surface configurations were illustrated. Accordingly, Mo and Ni are among the elements yielding lower adsorption energies, which are found to be À9.2626 and À5.2995 eV for substitutionally alloyed surfaces, respectively. In light of the dynamic calculations, Co as an alloying element is found to have a splitting effect on H 2 in 50 fs, where the first hydrogen atom is taken inside the Mg substrate right after the decomposition and the other after 1300 fs. An interesting remark is that, elements which acquire higher chances of adsorption are also seen to be competent at dissociating the hydrogen molecule. Furthermore, charge density distributions support the results of molecular dynamics simulations, by verifying the distinguished effects of most of the 3d and 4d transition metals
Magnetorheological damping and semi-active control of an autoparametric vibration absorber
Verification of the stability lobes of Inconel 718 milling by recurrence plot applications and composite multiscale entropy analysis
Doping-Free Arsenene Heterostructure Metal-Oxide-Semiconductor Field Effect Transistors Enabled by Thickness Modulated Semiconductor to Metal Transition in Arsenene
Two-dimensional (2-D) materials such as MoS2 and phosphorene provide an ideal platform to realize extremely thin body metal-oxide-semiconductor field effect transistors (MOSFETs) which is highly immune to short channel effects in the ultra-scaled regime. Even with the excellent electrostatic integrity inherent in 2-D system, however, 2-D materials suffer from the lack of efficient doping method which is crucial in MOSFETs technology. Recently, an unusual phase transition from semiconductor to metal driven by the thickness modulation has been predicted in mono-elemental 2-D material arsenene. Utilizing this extraordinary property, we propose doping-free arsenene heterostructure MOSFETs based on the lateral multilayer (metallic source)/monolayer (semiconducting channel)/multilayer (metallic drain) arsenene heterostructure. Metallic multilayer arsenene in the source and drain can serve as electrodes without doping. We investigate the potential performance of arsenene heterostructure MOSFETs through atomistic simulations using density functional theory and nonequilibrium Green's function. The intrinsic upper limit of the on-state current in arsenene heterostructure MOSFETs is estimated by studying the effect of layer number in the source and drain. We comprehensively analyze the competitiveness of arsenene heterostructure MOSFETs through benchmarking with monolayer arsenene homostructure MOSFETs equipped with the highly degenerate doped source and drain, suggesting superior performance of heterostructure MOSFETs over homostructure MOSFETs
Dexamethasone intravitreal implant in previously treated patients with diabetic macular edema : Subgroup analysis of the MEAD study
Background: Dexamethasone intravitreal implant 0.7 mg (DEX 0.7) was approved for treatment of diabetic macular edema (DME) after demonstration of its efficacy and safety in the MEAD registration trials. We performed subgroup analysis of MEAD study results to evaluate the efficacy and safety of DEX 0.7 treatment in patients with previously treated DME. Methods: Three-year, randomized, sham-controlled phase 3 study in patients with DME, best-corrected visual acuity (BCVA) of 34.68 Early Treatment Diabetic Retinopathy Study letters (20/200.20/50 Snellen equivalent), and central retinal thickness (CRT) 65300 \u3bcm measured by time-domain optical coherence tomography. Patients were randomized to 1 of 2 doses of DEX (0.7 mg or 0.35 mg), or to sham procedure, with retreatment no more than every 6 months. The primary endpoint was 6515-letter gain in BCVA at study end. Average change in BCVA and CRT from baseline during the study (area-under-the-curve approach) and adverse events were also evaluated. The present subgroup analysis evaluated outcomes in patients randomized to DEX 0.7 (marketed dose) or sham based on prior treatment for DME at study entry. Results: Baseline characteristics of previously treated DEX 0.7 (n = 247) and sham (n=261) patients were similar. In the previously treated subgroup, mean number of treatments over 3 years was 4.1 for DEX 0.7 and 3.2 for sham, 21.5 % of DEX 0.7 patients versus 11.1 % of sham had 6515-letter BCVA gain from baseline at study end (P = 0.002), mean average BCVA change from baseline was +3.2 letters with DEX 0.7 versus +1.5 letters with sham (P = 0.024), and mean average CRT change from baseline was -126.1 \u3bcm with DEX 0.7 versus -39.0 \u3bcm with sham(P < 0.001). Cataract-related adverse events were reported in 70.3 % of baseline phakic patients in the previously treated DEX 0.7 subgroup; vision gains were restored following cataract surgery. Conclusions: DEX 0.7 significantly improved visual and anatomic outcomes in patients with DME previously treated with laser, intravitreal anti-vascular endothelial growth factor, intravitreal triamcinolone acetonide, or a combination of these therapies. The safety profile of DEX 0.7 in previously treated patients was similar to its safety profile in the total study population
<Poster Presentation 5>Chaos in mechanical systems. Selected Problems
[Date] November 28 (Mon) - December 2 (Fri), 2011: [Place] Kyoto University Clock Tower Centennial Hall, Kyoto, JAPA
Autoparametric vibrations of a nonlinear system with pendulum
Vibrations of a nonlinear oscillator with an attached pendulum,
excited by movement of its point of suspension, have been analysed
in the paper. The derived differential equations of motion show
that the system is strongly nonlinear and the motions of both
subsystems, the pendulum and the oscillator, are strongly coupled
by inertial terms, leading to the so-called autoparametric
vibrations. It has been found that the motion of the oscillator,
forced by an external harmonic force, has been dynamically
eliminated by the pendulum oscillations. Influence of a nonlinear
spring on the vibration absorption near the main
parametric resonance region has been carried out analytically,
whereas the transition from regular to chaotic vibrations has been
presented by using numerical methods. A transmission force on the
foundation for regular and chaotic vibrations is presented as
well
Influences of system parameters on energy harvesting from autoparametric absorber. Numerical research
In the paper a numerical analysis of an autoparametric system is presented. The two main elements of a tested system are the pendulum (tuned mass absorber) and an energy harvester. The electromechanical model takes into account these both effects. Numerical simulations are made in a MATLAB software environment. The obtained results allowed estimation of influence of the system parameters on efficiency of energy harvesting