Chiral expansion and Macdonald deformation of two-dimensional Yang-Mills theory

We derive the analog of the large $N$ Gross-Taylor holomorphic string expansion for the refinement of $q$-deformed $U(N)$ Yang-Mills theory on a compact oriented Riemann surface. The derivation combines Schur-Weyl duality for quantum groups with the Etingof-Kirillov theory of generalized quantum characters which are related to Macdonald polynomials. In the unrefined limit we reproduce the chiral expansion of $q$-deformed Yang-Mills theory derived by de Haro, Ramgoolam and Torrielli. In the classical limit $q=1$, the expansion defines a new $\beta$-deformation of Hurwitz theory wherein the refined partition function is a generating function for certain parameterized Euler characters, which reduce in the unrefined limit $\beta=1$ to the orbifold Euler characteristics of Hurwitz spaces of holomorphic maps. We discuss the geometrical meaning of our expansions in relation to quantum spectral curves and $\beta$-ensembles of matrix models arising in refined topological string theory.Comment: 45 pages; v2: References adde

Ion beam effect on Ge-Se chalcogenide glass films: Non-volatile memory array formation, structural changes and device performance

The conductive bridge non-volatile memory technology is an emerging way to replace traditional charge based memory devices for future neural networks and configurable logic applications. An array of the memory devices that fulfills logic operations must be developed for implementing such architectures. A scheme to fabricate these arrays, using ion bombardment through a mask, has been suggested and advanced by us. Performance of the memory devices is studied, based on the formation of vias and damage accumulation due to the interactions of Ar+ ions with GexSe1-x (x=0.2, 0.3 and 0.4) chalcogenide glasses as a function of the ion energy and dose dependence. Blanket films and devices were created to study the structural changes, surface roughness, and device performance. Raman Spectroscopy, Atomic Force Microscopy (AFM), Energy Dispersive X-Ray Spectroscopy (EDS) and electrical measurements expound the Ar+ ions behavior on thin films of GexSe1-x system. Raman studies show that there is a decrease in area ratio between edge-shared to corner-shared structural units, revealing occurrence of structural reorganization within the system as a result of ion/film interaction. AFM results demonstrate a tendency in surface roughness improvement with increased Ge concentration, after ion bombardment. EDS results reveal a compositional change in the vias, with a clear tendency of greater interaction between ions and the Ge atoms, as evidenced by greater compositional changes in the Ge rich films

Comparative Microstructural Study of the Diffusion Zone Between Ni-Cr Alloy and Different Dental Ceramics

Detailed knowledge of bonding mechanisms, between the metal and ceramic parts in conventional dental systems, can help the development of new, improved systems and the optimisation of recent technologies. Despite their allergic potential, the NiCr alloys are still amongst the most often used dental materials so their investigation is important. The aim of the study was to carry out a detailed microstructural investigation and to compare the reaction layer developed between three different dental ceramics and NiCr alloy under different firing conditions. For the measurements six identical samples were cast from WIRON 99 (Bego, Konstantz, Germany) alloy. Ceramic opaquers were fired on the polished surface using Vision (Wohlwend AG), Vita VMK 95 (Vita) and Carat(DeTrey/Dentsplay) materials. Two samples were produced from each type of opaquers by different firing conditions. The TEM investigations were performed by using a 2000FX-II microscope with a Link-lsis EDS system. Similar growth processes of the phases were observed in all of the investigated systems in the sense that an amorphous phase was formed on the metal-ceramic interface producing bubble like inclusions on the metal surface. The main component of this phase is silicon oxide in the case of Carat and Vita ceramics, while in the case of Vision potassium and nickel oxides were observed after the normal firing process. In all systems and at all firing conditions a nanocrystalline Cr2O3 layer (with about 50 nm grain size) was commonly observed. This investigation was supported in part by ETT Grant 2001-3

Stimulated structural changes of Se in nanolayered composite films

International audienceAmorphous selenium (a-Se) is the simplest model material for investigation of the well-known photoinduced structural and optical transformations in amorphous chalcogenides. Since a lot of parameters and characteristics of materials essentially change at nanoscale, we applied nanostructuring to a -Se in nanomultilayers, obtained by pulsed laser deposition. The enhancement of photo- and thermally-induced crystallization was observed in a-Se/aluminosilicate nanomultilayers due to the initially heterogeneous state of Se in such samples, in comparison with single a -Se layers

Arsenic trisulfide-doped silica-based porous glass

Novel composite material based on silica porous glass as low refractive index matrix and high refractive index As2S3 nanoparticles filled in the pores has been made. Chalcogenide nanoparticles were dissolved and the porous glass matrix was impregnated in the obtained solution. Subsequently, the solvent was evaporated by annealing the porous glass. Various optical parameters of the created composite material are presented in this paper. These parameters are based on optical and structural transformations which occur under active illumination and heat treatment in such chalcogenide-containing composite and compared with thin As2S3 light-sensitive layers. New functionalities may be added this way to the composite, such as illumination and/or thermally driven optical parameters. Developing and optimizing the optical properties of the obtained As2S3-porous glass composites can be useful for creating 3D optical-structural patterns for different applications such as holographic data storage, light modulation, and/or functional, nonlinear optical elements with various parameters for VIS-NIR optics