K3 surfaces with non-symplectic automorphisms of 2-power order

This paper concerns complex algebraic K3 surfaces with an automorphism which acts trivially on the Néron–Severi group. Complementing a result by Vorontsov and Kondō, we determine those K3 surfaces where the order of the automorphism is a 2-power and equals the rank of the transcendental lattice. We also study the arithmetic of these K3 surfaces and comment on relations with mirror symmetry.     

Synthesis of, light emission from, and optical power limiting in soluble single-walled carbon nanotubes functionalized by disubstituted polyacetylenes

Single-walled carbon nanotubes are covalently functionalized by conjugated polyacetylenes through their cyclization reactions with poly(1-phenyl-1-alkyne) and poly(diphenylacetylene) derivatives carrying azido functional groups at the ends of their alkyl pendants. The resultant polyene nanotube addends are soluble in common solvents, emit intense visible lights and strongly attenuate the power of harsh laser pulses.     

Probing electron transfer dynamics at MgO surfaces by Mg-atom desorption

Ultraviolet excitation of high surface area MgO films using 4.7 eV femtosecond pulses results in neutral Mg-atom desorption with hyperthermal kinetic energies in the range 0.1-0.4 eV. The Mg-atom hyperthermal energies and power dependences are similar to those previously observed using nanosecond pulsed excitation. Femtosecond two-pulse correlation measurements reveal the existence of different dynamical paths for Mg-atom desorption. One mechanism displays a sub-150 fs time scale and involves the simultaneous or near-simultaneous transition of two electrons to a 3-coordinated Mg(2+) site. Other paths display picosecond time scales that we associate with dynamics following electron trapping at 3-coordinated Mg(2+) surface sites.     

New synthetic protocols for the preparation of unsymmetrical bisindoles

Novel unsymmetrical bisindoles were synthesized by a solvent-free C-C bond-formation reaction under mild conditions. Starting from aziridines or hydroxyl precursors, indoles have been used as C-nucleophiles to form new pharmacologically interesting bisindoles via an electrophilic aromatic substitution pathway in good to excellent yields. [reaction: see text]     

State tomography of capacitively shunted phase qubits with high fidelity

We introduce a new design concept for superconducting phase quantum bits (qubits) in which we explicitly separate the capacitive element from the Josephson tunnel junction for improved qubit performance. The number of two-level systems that couple to the qubit is thereby reduced by an order of magnitude and the measurement fidelity improves to 90%. This improved design enables the first demonstration of quantum state tomography with superconducting qubits using single-shot measurements.     

An implicit approach to predict the dynamics of granular media

The objective of this study is to present an implicit method to predict the dynamics of granular particles. In the proposed methodology, the dynamics equation of colliding particles are solved implicitly which means the positions of particles at the next time step are also used to compute the next state of the particles. This is in contrast with the explicit approach where only known i.e. past information is used to calculate the new positions. The method is tested in a simple setting where a spherical particle is in continuous movement between two boundary walls. The results show that considerably larger time steps are enabled with the implicit method compared to the explicit method. Future work will compare the overall efficiency of the implicit and explicit methods in more detail. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

ChemInform Abstract: X2Y2 Isomers: Tuning Structure and Relative Stability Through Electronegativity Differences (X: H,Li, Na,F, Cl,Br, I; Y: O,S, Se,Te).

Density functional calculations on XYYX and X₂YY isomers of the X₂Y₂ species (X: H, Li, Na, F, Cl, Br, I; Y: O, S, Se, Te) show that the XYYX isomers are more stable than the X₂YY forms except for X = F and Y = S and Te, for which the F₂SS and F₂TeTe isomers are slightly more stable.     

Electric–magnetic duality of lattice systems with topological order

We investigate the duality structure of quantum lattice systems with topological order, a collective order also appearing in fractional quantum Hall systems. We define electromagnetic (EM) duality for all of Kitaev?s quantum double models based on discrete gauge theories with Abelian and non-Abelian groups, and identify its natural habitat as a new class of topological models based on Hopf algebras. We interpret these as extended string-net models, whereupon Levin and Wen?s string-nets, which describe all intrinsic topological orders on the lattice with parity and time-reversal invariance, arise as magnetic and electric projections of the extended models. We conjecture that all string-net models can be extended in an analogous way, using more general algebraic and tensor-categorical structures, such that EM duality continues to hold. We also identify this EM duality with an invertible domain wall. Physical applications include topology measurements in the form of pairs of dual tensor networks.