The well-known recurrent nova T Pyx has brightened by 7 magnitudes, starting on 2011 April 14, its first eruption since 1966. T Pyx is unique amongst recurrent novæ in being surrounded by a nebula formed of material ejected during previous eruptions. The latest eruption therefore offers the rare opportunity to observe a light echo sweeping through the existing shell, and a new one forming. The sudden exposure of the existing shell to high-energy light is expected to result in a change of the dust morphology as well as in the part destruction of molecules. We observe this process in the near- and mid-IR during several epochs using ESO's VLT instruments Sinfoni, Visir and Isaac. Unfortunately, in the data analysed so far we only have a tentative detection in Brα from the shell, so might in the end have to be content with upper limits for the emission from the various molecular bands and ionised lines.

Atomic layer deposition (ALD) is ideal for applying precise, conformal coatings over nanoporous materials. We have recently used ALD to coat two nanoporous solids: anodic aluminum oxide (AAO) and silica aerogels. AAO possesses hexagonally ordered pores with diameters d∼10 nm and thicknesses L∼70 microns. The AAO membranes were coated by ALD with successive layers of A1203, TiO2 and V2O5 to fabricate catalytic membranes. SEM, TEM and EDAX analysis of the membranes demonstrate that the ALD layers uniformly coat the extremely high aspect ratio (L/d∼104) AAO pores. These catalytic membranes show remarkable selectivity in the oxidative dehydrogenation of cyclohexane. Additional AAO membranes coated with ALD Pd films show promise as hydrogen sensors. Silica aerogels have the lowest density and highest surface area of any solid material. Consequently, these materials serve as an excellent substrate to fabricate novel catalytic materials and gas sensors by ALD. In this study, both thin film and monolithic aerogels were coated by ZnO ALD and the properties of the aerogels were investigated as a function of the coating thickness.

We have carried out experiments on dual-damascene Cu interconnects with different lengths. We find that at short lengths, similar to Al-based interconnects, the reliability of Cubased interconnects improves. Also like Al interconnects, some short Cu segments do not form voids that cause failure before back-stresses prevent the further growth of voids. However, unlike Al-based interconnects, there is no apparent deterministic current-density line-length product (jL) for which all lines are immortal. This is related to the absence of a conducting refractory-metal overlayer in Cu-technology that can shunt current around small voids. Also unlike Al, we find that at long lengths a sub-population of Cu lines is immortal. We propose that this is the result of rupture of the thin refractory metal liner at the base of the dual-damascene Cu vias. As a consequence of this complex behavior, median times to failure and lifetime variations are minimum at intermediate line lengths.

Las ruinas de Calakmul se encuentran en la cuenca del mismo nombre localizado dentro del 723,000 ha Reserva de la Biosfera Calakmul en el sureste del Estado de Campeche. Investigaciones del Centro de Investigaciones Históricas y Sociales de la Universidad Autónoma de Campeche han demostrado que Calakmul formaba una de las más grandes centros regionales en el área maya desde 600 a.C. hasta los fines del siglo IX dentro de su estado regional de 13,000 km2. Investigaciones de prospección remoto alrededor de Calakmul combinado con trabajos topográficos dentro de la ciudad misma han revelado 15 sac beob identificados por nosotros entre los tipos de vías terrestres descritos en los diccionarios de la idioma Maya formados durante el período colonial. Entre estos sac beob se encuentran tipos regionales, estatales y los sac beob registrados dentro de la ciudad de Calakmul. Aunque existe un traslapo entre varios tipos de sac beob, pensamos que excavaciones futuras van a ayudarnos a clasificar cada sac be en una forma más precisa.

We previously reported the synthesis and some properties of heterostructure nanoparticles, i.e. CdS coated with PbS (CdS/PbS). We report further characterization and investigation of the infrared photoluminescence (PL) of the CdS and coated CdS/PbS nanoparticles. This allows us to provide a more stringent test of the quantum confinement model. We consider the energy shift of the PL peak and the variation of the PL intensity correlated with the predictions of the quantum confinement model. The experimental results can be explained by this model of coated semiconductor nanoparticles.

Nanometer size semiconductor particles coated with another semiconductor can exhibit unusual and interesting phenomena associated with the redistribution of the electron and hole wavefunctions. Using the band offsets and effective-masses, the band gap as well as the wavefunctions can be altered by changing the core radius of the particles. CdS/PbS coated semiconductor nanoparticles are synthesized by ion displacing method and experimental results are discussed along with the theoretical calculation. Optical absorption as well as TEM, Electron diffraction results provides for the evidence that the particles are coated.

In this paper we report the synthesis of Au2S nanoparticles with a gold coating on the surface; the particles are characterized by transmission electron microscopy (TEM), electron diffraction and absorption data. The absorption spectrum is recorded during the gold coating growth process; this data demonstrates a large resonance shift during the growth process. The results are consistent with the growth of a metal shell around the particles; the theoretical model includes electron quantum confinement in the metal shell. The size dependence of the frequency shift, as well as the width of the resonance are consistent with the model.

The syntheses and physical properties of K-(ET)2CU[N(CN)2]X (X = Br and Cl) are summarized. The K-(ET)2Cu [N(CN)2] Br salt is the highest Tc radical-cation based ambient pressure organic superconductor (Tc = 11.6 K), and the K-(ET)2CU [N(CN)2] C1 salt becomes a superconductor at even higher Tc under 0.3 kbar hydrostatic pressure (Tc = 12.8 K). The similarities and differences between K-(ET)2Cu[N(CN)2]Br and K-(ET)2CU(NCS)2 (TC = 10.4 K) are presented. The X-ray structures at 127 K reveal that the S-S contacts shorten between ET dimers in the former compound while the S-S contacts shorten within dimers in the latter. The differences in their ESR linewidth behavior is also explained in terms of the structural differences. A semiconducting compound, (ET)Cu[N(CN)2]2, isolated during K-(ET)2Cu[N(CN)2]Cl synthesis is also reported. The ESR measurements of the K-(ET)2Cu[N(CN)2]Cl salt indicate that the phase transition near 40 K is similar to the spin density wave transition in (TMTSF)2SbF6. A new class of organic superconductors, K-(ET)2CU2(CN)3 and K-(ET)2Cu2(CN)3.δBrδ, is reported with Tc's of 2.8 K (1.5 kbar) and 2.6 K (1 kbar), respectively.

High field magnetization experiments are reported for dilute Zn1−xMnxTe alloys (x≃0.03) at T=1.3K. The first magnetization step is analyzed including effects of internal field due to the interactions of Mn-Mn pairs with the remaining spins. An accurate estimate of the nearest neighbor (NN) exchange constant is obtained which agrees quite well recent neutron scattering experiments.