Formation of a regular fullerene nanochain lattice

A vicinal Au(11 12 12) surface, naturally patterned into a rectangular superlattice, has been used as a template to prepare C60 nanostructures with long-range order and uniform size. At a coverage of 0.1 monolayer and at room temperature, a two-dimensional long-range ordered superlattice of molecular nanochains is achieved, which perfectly replicates the periodicity of the template surface. The fullerene nanochains are found to be located exclusively on the face-centered cubic stacking domains at the lower step edges. Our experiments demonstrate that highly periodic molecular nanochains can be fabricated through a site-selective anchoring method.     

Nonlinear study of a rotor–AMB system under simultaneous primary-internal resonance

A rotor–active magnetic bearing (AMB) system subjected to a periodically time-varying stiffness with quadratic and cubic non-linearities under multi-parametric excitations is studied and solved. The method of multiple scales is applied to analyze the response of two modes of a rotor–AMB system with multi-parametric excitations and time-varying stiffness near the simultaneous primary and internal resonance. The stability of the steady state solution for that resonance is determined and studied using Rung–Kutta method of fourth order. It is shown that the system exhibits many typical non-linear behaviors including multiple-valued solutions, jump phenomenon, hardening and softening non-linearities and chaos in the second mode of the system. The effects of the different parameters on the steady state solutions are investigated and discussed also. A comparison to published work is reported.     

A monolithic finite element discretization for coupled Darcy-Stokes flow

We consider a Stokes system and a Darcy system in a porous media, mutually coupled together by the the well-known Beaver-Joseph-Saffman interface conditions. Standard approaches use different finite elements in the two parts in order to account for the different stability properties of the two equation systems. In contrast to this, we use standard equal-order finite elements in both parts. Stability is obtained by adding local projection terms (LPS) to the Galerkin formulation. We formulate the scheme and give an a priori estimate. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Bayesian estimation of the product of two proportions

Suppose that for i = 1,2, a Bernoulli random variable with success probability θ_i is observable from population i. The problem is to estimate θ = θ₁θ₂ using a Bayesian approach with squared error estimation loss in θ. For estimating θ, the best nonrandom sampling scheme, the two-stage sampling scheme, and the optimal sampling scheme are discussed. It is shown that the two-stage sampling scheme is typically asymptotically optimal, and can improve the Bayes risk (over the best nonrandom allocation) up to fifty percent     

A facile synthesis of pyrrolo[3,2‐d]pyrimidines from 6‐azidouracils and ylide phosphoranes

A series of the title compounds, 9‐deazaxanthines, was regioselectively prepared in reasonable yields as major products from the reactions of 6‐azidouracils 1a,b with stabilized ester‐ 2a,b or keto‐ 2c ylide phosphoranes and a moderated phosphorus ylide 3 , instead of the expected triazoles. Side products were also observed wherein pyrimido[5,4‐g]pteridine‐2,4,5,7‐tetrone ( 15 ) and other fused ring systems or acyclic‐substituted uracil derivatives were isolated. A comparative study on the reactivity of 1a in analogy to 1b toward phosphoranes is also described. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:357–365, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10048     

Proton related defects in α-BaTiO3:H films based MIM capacitors

Hydrogenated barium titanate film based metal–insulator–metal (MIM) systems show high dielectric constant and have therefore been proposed as solid state supercapacitors. Hydrogen was incorporated in the dielectric layer during the low temperature deposition process. An investigation of the electrical properties has revealed that hydrogen contributes to the conduction process as mobile ionic species as well as donor trap levels.     

A novel design approach for the epitaxial layer for 4H-SiC and 6H-SiC power bipolar devices

The paper evaluates the optimal design of the low-doped base region inside power diodes and other bipolar devices. It is demonstrated theoretically that a low-doped base region of P⁺N⁻N⁺ diodes can provide a high breakdown voltage and an optimal on-resistance . A simple, accurate and CPU timesaving approach is presented to extract an optimal value for the base region width, W_B, and its doping concentration, N_D. The paper details an analytical relation between W_B and N_D, and gives a method for quantifying the trade-off between their values for a given breakdown voltage and for obtaining the minimal on-resistance. Analytical results are confronted with experimental results for 4H-SiC- and 6H-SiC-based diodes.     

Effect of the TiO2 reduction state on the catalytic CO oxidation on deposited size-selected Pt clusters

The catalytic activity of deposited Pt(7) clusters has been studied as a function of the reduction state of the TiO(2)(110)-(1 × 1) support for the CO oxidation reaction. While a slightly reduced support gives rise to a high catalytic activity of the adparticles, a strongly reduced one quenches the CO oxidation. This quenching is due to thermally activated diffusion of Ti(3+) interstitials from the bulk to the surface where they deplete the oxygen adsorbed onto the clusters by the formation of TiO(x) (x ? 2) structures. This reaction is more rapid than the CO oxidation. The present results are of general relevance to heterogeneous catalysis on TiO(2)-supported metal clusters and for reactions involving oxygen as intermediate.