Polarization splitter based on a square-lattice photonic-crystal fiber

A three-core polarization splitter based on a square-lattice photonic-crystal fiber is presented. The component separates the input field into two orthogonally polarized beams that are coupled to the horizontal and vertical output ports. The splitter has been designed through modal and beam propagation analysis by employing high-performance codes based on the finite-element method. Results obtained for a device length of 20 mm show extinction ratios as low as -23 dB with bandwidths as great as 90 nm.     

Simultaneous near field imaging of electric and magnetic field in photonic crystal nanocavities

The insertion of a metal-coated tip on the surface of a photonic crystal microcavity is used for simultaneous near field imaging of electric and magnetic fields in photonic crystal nanocavities, via the radiative emission of embedded semiconductor quantum dots (QD). The photoluminescence intensity map directly gives the electric field distribution, to which the electric dipole of the QD is coupled. The magnetic field generates, via Faraday's law, a circular current in the apex of the metallized probe that can be schematized as a ring. The resulting magnetic perturbation of the photonic modes induces a blue shift, which can be used to map the magnetic field, within a single near-field scan.     

Ideal homoatomic and heteroatomic photonic crystal molecules

A local tuning of the modes of photonic crystal systems both to blue and to red sides of the resonance is implemented by nano-infiltration/evaporation of water and laser micro-oxidation. This technology is used to completely control coupled photonic nanocavities (photonic crystal molecules). Beside the standard condition of zero detuning between identical modes of the two cavities (homoatomic molecule), we are also able to produce coupling between two modes of different polarization and spatial distribution (heteroatomic molecule).     

Dynamic spatial price equilibrium problem: regularity results and computational procedure

In this paper we consider the dynamic spatial price equilibrium problem and the associated evolutionary variational inequality. In particular the regularity of equilibrium solutions is studied and a method for solving the dynamic spatial price equilibrium problem is presented. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preface to Variational Analysis for Beginners

Set-Valued and Variational Analysis -     

Product integration for volterra integral equations of the second kind with weakly singular kernels

We introduce a new numerical approach for solving Volterra integral equations of the second kind when the kernel contains a mild singularity. We give a convergence result. We also present numerical examples which show the performance and efficiency of our method.

     

The chaperonin of the archaeonSulfolobus solfataricus

The chaperonin of the hyperthermophilic archaeonSulfolobus solfataricus, briefly Ssocpn, was purified by a fast and high-yield procedure. Ssocpn, a 920 kDa-complex of two different subunits, displays a potassium-dependent ATPase activity with a temperature optimum at 80°C. The ability of Ssocpn to function in vitro was investigated using different protein substrates. Ssocpn promotes correct refolding of thermophilic and mesophilic enzymes from their chemically unfolded state; moreover, Ssocpn prevents the irreversible inactivation of native proteins by suppressing their precipitation upon heating. Both the activity in assisting refolding of unfolded proteins and that in preventing heat denaturation of native proteins require the hydrolysis of ATP. The chaperone-based strategies in different technological fields are discussed, and the advantages in using archaeal chaperonins are underlined.     

New synthesis and X-ray diffraction study of a polymeric form of Ag(I) dithio-o-toluato, [Ag4(S2C-o-C6H4CH3)4]n

The title compound was synthesized by CS₂ insertion in the C-M bonds of the corresponding AgLi ate organomental compound. It contains flattened tetrahedral Ag₄ units, connected in polymeric chains by intermolecular Ag...S interactions. Two Ag atoms and three S atoms are in a distorted square pyramidal arrangement around each silver atom. The crystals are tetragonal, space group 14₁/a witha=23.706(2) andc=12.934(2) Å. The structure was refined toR=0.032 for 889 reflections.     

(n-C5H5) (CO)2W{n3-C5H5[(n-C5H4)2Fe]} - ein neuer Fe und N enthaltender Zweikernkomplex

(η-C₅H₅)(CO)₂W[(η³-C₅H₅)(C₅H₅)₂], I, containing two tilted five-membered rings, is converted into the bridged ferrocene derivative (η-C₅H₅)(CO)₂W{(η³-C₅H₅)}[(η-C₅ H₄)₂Fe]} II by successive reaction with Na and FeCl₂.     

Synthesis of alpha-acyl-functionalized azacycles by Pd-catalyzed cross-coupling reactions of alpha-alkoxyboronates with lactam-derived vinyl triflates

Alkoxydienyl- and alkoxystyrylboronates were used for Pd-catalyzed cross-coupling reactions with lactam-derived vinyl triflates. The hydrolysis of the coupling products with alkoxystyrylboronates provided the corresponding alpha-acyl-substituted 3,4-dihydro-(2H)-pyridines and 2,3,4,5-tetrahydroazepines in good to high yields. The hydrolysis of the coupling products with alkoxydienylboronates, performed in the presence of Amberlyst 15, resulted in a Nazarov-type cyclization that afforded hexahydro[1]pyrindin-7-ones and 3,4,5,6,7,8-hexahydro-(2H)-cyclopenta[b]azepin-8-ones. This methodology represents a novel and efficient procedure for the preparation of these classes of azacyclic compounds.