Double quantization of CP type orbits by generalized Verma modules

It is known that symmetric orbits in g^* for any simple Lie algebra g are equipped with a Poisson pencil generated by the Kirillov-Kostant-Souriau bracket and the reduced Sklyanin bracket associated to the “canonical” R-matrix. We realize quantization of the Poisson pencil CPⁿ type orbits (i.e. orbits in sl(n + 1)^* whose real compact form is CPⁿ) by means of q-deformed Verma modules.     

Extra-drude contribution to the far infrared conductivity oxygen deficient YBCO films

We measured reflectance spectra R(v) of oxygen deficient Y₁Ba₂Cu₃O_7–x (YBCO) films of different thickness, with critical temperatures between 85 and 87 K. Measurements were made at room temperature between 15 and 25000 cm^–1. The measured R(v) have a maximum below 100 cm^–1 and then decrease for v 0. This low frequency behaviour of R(v) can be accounted for by considering a relevant extra-Drude contribution to the far infrared optical conductivity of YBCO.     

VUV light induced surface interaction and accelerated diffusion of carbon, silicon, oxygen and other contaminants in LiF crystals

One hundred and fifty-seven nanometers irradiation of LiF crystals accelerates the penetration of C, O, N, Si and other contaminants within the crystal bulk. New bonding between the contaminant elements in both the irradiated and the non-irradiated areas of the crystal was identified. The chemical changes eventually form inhomogeneous nano/micro-islands, which further agglomerate to larger structures in the form of an interfacial layer. The concentration and diffusion (∼100 nm) of contaminants in the irradiated part of the crystal is higher than for the non-irradiated one. The accelerated diffusion is due to a force perpendicular to the crystal surface. This force is generated by the laser's electric field gradient in the direction of beam propagation due to the inhomogeneous absorption at the interfacial layer. A theoretical diffusion model in the presence of the laser field allows rationalizing and interpreting the experimental results.     

Development of a photosystem II-based optical microfluidic sensor for herbicide detection

Herbicides are highly toxic for both human and animal health. The increased application of herbicides in agriculture during the last decades has resulted in the contamination of both soil and water. Herbicides, under illumination, can inhibit photosystem II electron transfer. Photosynthetic membranes isolated from higher plants and photosynthetic micro-organisms, immobilized and stabilized, can serve as a biorecognition element for a biosensor. The inhibition of photosystem II causes a reduced photoinduced production of hydrogen peroxide, which can be measured by a chemiluminescence reaction with luminol and the enzyme horseradish peroxidase. In the present work, a compact and portable sensing device that combines the production and detection of hydrogen peroxide in a single flow assay is proposed for herbicide detection.     

Cation mass dependence of the nearly constant dielectric loss in alkali triborate glasses

Electrical ac conductivity measurements on alkali triborate glasses ( M2O x 3B2O3, M = Li, Na, K, and Rb) were performed at temperatures down to 8 K and frequencies up to 1 GHz. All samples show a nearly constant dielectric loss (NCL), at the limit of high frequencies and/or low temperatures. The magnitude of the NCL is found to decrease as m(-1/3) with increasing alkali ion mass m. This quantitative result for the NCL, closely related to the mean-square displacement of ions, indicates that the origin of the NCL might be related to vibrational relaxation of the ions in the anharmonic potentials that cage them, and the cage is decaying very slowly with time.     

Effect of synthesis method on the structure and properties of AgPO3-based glasses

The relation between ionic conductivity, glass transition temperature and structure has been investigated in silver-metaphosphate, AgPO₃, glasses synthesized under varying conditions. The key finding of this work concerns the AgPO₃ doping with up to 3 mol.% Al₂O₃ when melting is done in alumina crucibles, a practice used widely for the synthesis of fast ion conducting glasses. Vibrational spectroscopy showed that Al₂O₃-doping increases the phosphate network connectivity by P-O-Al-O-P cross-links. This effect causes a drastic enhancement in ionic conductivity and glass transition temperature relative to Al₂O₃-free AgPO₃ glasses obtained by melting in Pt crucibles.     

Composition and temperature dependence of cesium-borate glasses by molecular dynamics

The structural aspects of xCs2O-(1-x)B2O3 glasses have been investigated by molecular dynamics as functions of Cs2O content (x=0.2, 0.3, and 0.4) and temperature (T=300 and 1250 K). The tetrahedral (B?4-) and triangular (B?3,B?2O-, and B?O2 (2-)) short-range order borate units were found to be the structure-building entities of the simulated glasses [?=bridging oxygen (BO) and O-=nonbridging oxygen (NBO) atom]. The increase of Cs2O content results in the progressive increase of the NBO-containing triangle population at the expense of the BO4- tetrahedral units. The same effect is caused by temperature increase at a fixed Cs2O content, and this was associated with the "fragile" characteristics of alkali borate glasses. A comparison of simulated Cs and Li borates showed very similar structures at x=0.2, but dissimilar ones when the alkali content exceeds this composition. In particular, for x>0.2 Cs borates exhibit a preference for NBO formation relative to Li borates. Differences in the microstructure of sites hosting Cs ions were found, and this permits their classification into bridging (b type) and nonbridging type (nb type) of sites. b-type sites consist exclusively of BO atoms, while both BO and NBO atoms participate in nb-type sites. These differences in Cs-site local bonding characteristics were found to be reflected on the Cs-O(site) vibration frequencies. Also, the computed Cs-O vibrational responses for simulated Cs borates were found to compare well with experimental far-infrared spectra.