Probing equilibrium glass flow up to exapoise viscosities

Glasses are out-of-equilibrium systems aging under the crystallization threat. During ordinary glass formation, the atomic diffusion slows down rendering its experimental investigation impractically long, to the extent that a timescale divergence is taken for granted by many. We circumvent here these limitations, taking advantage of a wide family of glasses rapidly obtained by physical vapor deposition directly into the solid state, endowed with different "ages" rivaling those reached by standard cooling and waiting for millennia. Isothermally probing the mechanical response of each of these glasses, we infer a correspondence with viscosity along the equilibrium line, up to exapoise values. We find a dependence of the elastic modulus on the glass age, which, traced back to temperature steepness index of the viscosity, tears down one of the cornerstones of several glass transition theories: the dynamical divergence. Critically, our results suggest that the conventional wisdom picture of a glass ceasing to flow at finite temperature could be wrong.Comment: 4 figures and 1 supplementary figur

Cathodoluminescence and photoluminescence of highly luminescent CdSe/ZnS quantum dot composites

We report room-temperature cathodoluminescence and photoluminescence spectra originating from ZnS overcoated CdSenanocrystals, 33 and 42 Å in diameter, embedded in a ZnS matrix. The thin-filmquantum dot composites were synthesized by electrospray organometallic chemical vapor deposition.Cathodoluminescence and photoluminescence are dominated by the sharp band-edge emission characteristic of the initial nanocrystals. The emission wavelength can be tuned in a broad window (470-650 nm) by varying the size of the dots. The cathodoluminescence intensity depends on the crystallinity of the ZnS matrix and the voltage and current density applied

Growth monitoring with sub-monolayer sensitivity via real time thermal conductance measurements

Growth monitoring during the early stages of film formation is of prime importance to understand the growth process, the microstructure and thus the overall layer properties. In this work, we demonstrate that phonons can be used as sensitive probes to monitor real time evolution of film microstructure during growth, from incipient clustering to continuous film formation. For that purpose, a silicon nitride membrane-based sensor has been fabricated to measure in-plane thermal conductivity of thin film samples. Operating with the 3{\omega}-V\"olklein method at low frequencies, the sensor shows an exceptional resolution down to {\Delta}({\kappa}*t)=0.065 nm*W/(m*K), enabling accurate measurements. Validation of the sensor performance is done with organic and metallic thin films. In both cases, at early stages of growth, we observe an initial reduction of the effective thermal conductance of the supporting amorphous membrane, K, related with the surface phonon scattering enhanced by the incipient nanoclusters formation. As clusters develop, K reaches a minimum at the percolation threshold. Subsequent island percolation produces a sharp increase of the conductance and once the surface coverage is completed K increases linearly with thickness The thermal conductivity of the deposited films is obtained from the variation of K with thickness

Influence of layer microstructure on the double nucleation process in Cu/Mg multilayers

9 páginas, 9 figuras, 3 tablas.-- et al.We have investigated by differential scanning calorimetry the thermal evolution of Cu/Mg multilayers with different modulation lengths, ranging from 7/28 to 30/120 nm. The Cu and Mg layers were grown by sequential evaporation in an electron beam deposition system. The phase identification and layer microstructure were determined by cross-section transmission electron microscopy, Rutherford backscattering, and scanning electron microscopy with focused ion beam for sample preparation. Upon heating, the intermetallic CuMg2 forms at the interfaces until coalescence is reached and thickens through a diffusion-limited process. Cross-section transmission electron microscopy observations show a distinct microstructure at the top and bottom of the as-prepared Mg layers, while no significant differences were seen in the Cu layers. We show that this effect is responsible for the observed asymmetry in the nucleation process between the Cu on Mg and the Mg on Cu interfaces. By modeling the calorimetric data we determine the role of both interfaces in the nucleation and lateral growth stages. We also show that vertical growth proceeds by grain development of the product phase, increasing significantly the roughness of the interfaces.The financial support by Project No. MAT2004-04761 granted by the Spanish Ministry of Education and 2005SGR00201 granted by the Direcció General de Recerca of the Generalitat of Catalonia is acknowledged. One of the authors (J.L.L.) acknowledges the financial support from the Hungarian National Science Fund (OTKA043437).Peer reviewe

An open prospective study on the efficacy of Navina Smart, an electronic system for transanal irrigation, in neurogenic bowel dysfunction

Background: Transanal irrigation (TAI) has emerged as a key option when more conservative bowel management does not help spinal cord injured (SCI) individuals with neurogenic bowel dysfunction (NBD). Aim: To investigate the short-term efficacy and safety of an electronic TAI system (Navina Smart) in subjects with NBD. Design: We present an open, prospective efficacy study on Navina Smart, in individuals with NBD secondary to SCI, studied at three months. Population: Eighty-nine consecutive consenting established SCI individuals (61 male; mean age 48, range 18–77) naïve to TAI treatment were recruited from ten centres in seven countries. Subjects had confirmed NBD of at least moderate severity (NBD score ≥10). Methods: Subjects were taught how to use the device at baseline assisted by the Navina Smart app, and treatment was tailored during phone calls until optimal TAI regime was achieved. The NBD score was measured at baseline and at three months follow up (mean 98 days). Safety analysis was performed on the complete population while per protocol (PP) analysis was performed on 52 subjects. Results: PP analysis showed a significant decrease in mean NBD score (17.8 to 10, p<0.00001). In subjects with severe symptoms (defined as NBD score ≥14), mean NBD scores decreased (19.4 to 10.9, p<0.0001). The number of subjects with severe symptoms decreased from 41 (79%) subjects at baseline to 16 (31%) at three months follow-up. Device failure accounted for the commonest cause for loss of data. Side effects possibly related to the device developed in 11 subjects (12%). Discontinuation due to failure of therapy to relieve symptoms was reported by 5 subjects (6%). Conclusion: Navina Smart is effective for individuals with NBD, even those with severe symptoms; long-term data will follow. Whilst there were some device problems (addressed by the later stages of subject recruitment) the treatment was generally safe

An open prospective study on the efficacy of Navina Smart, an electronic system for transanal irrigation, in neurogenic bowel dysfunction

Background: Transanal irrigation (TAI) has emerged as a key option when more conservative bowel management does not help spinal cord injured (SCI) individuals with neurogenic bowel dysfunction (NBD). Aim: To investigate the short-term efficacy and safety of an electronic TAI system (Navina Smart) in subjects with NBD. Design: We present an open, prospective efficacy study on Navina Smart, in individuals with NBD secondary to SCI, studied at three months. Population: Eighty-nine consecutive consenting established SCI individuals (61 male; mean age 48, range 18–77) naïve to TAI treatment were recruited from ten centres in seven countries. Subjects had confirmed NBD of at least moderate severity (NBD score ≥10). Methods: Subjects were taught how to use the device at baseline assisted by the Navina Smart app, and treatment was tailored during phone calls until optimal TAI regime was achieved. The NBD score was measured at baseline and at three months follow up (mean 98 days). Safety analysis was performed on the complete population while per protocol (PP) analysis was performed on 52 subjects. Results: PP analysis showed a significant decrease in mean NBD score (17.8 to 10, p<0.00001). In subjects with severe symptoms (defined as NBD score ≥14), mean NBD scores decreased (19.4 to 10.9, p<0.0001). The number of subjects with severe symptoms decreased from 41 (79%) subjects at baseline to 16 (31%) at three months follow-up. Device failure accounted for the commonest cause for loss of data. Side effects possibly related to the device developed in 11 subjects (12%). Discontinuation due to failure of therapy to relieve symptoms was reported by 5 subjects (6%). Conclusion: Navina Smart is effective for individuals with NBD, even those with severe symptoms; long-term data will follow. Whilst there were some device problems (addressed by the later stages of subject recruitment) the treatment was generally safe

Electron beam induced current and scanning tunnelling spectroscopy correlative study of Cd-xHg_(1-x)Te and CdTe crystals

A combined scanning electron microscope-scanning tunnelling microscope (SEM-STM) system has been used to characterize CdxHg1-xTe and CdTe crystals, The electron beam induced current (EBIC) mode of the SEM shows the existence of inhomogeneities in the electronic behaviour of the samples, mainly related to the presence of subgrain boundaries and precipitates. Current imaging tunnelling spectroscopy images and the related normalized differential conductance curves, obtained with the STM, reveal the electronic inhomogeneities at a finer scale. In particular, local variations of the band gap were shown by the conductance curves in regions with strong EBIC contrast. SEM-and STM-based techniques in a combined instrument appear to be complementary characterization techniques

Nuevas categorías de trofeos de venado cola blanca (odocoileus virginianus) del safari club internacional, para México

  The white-tailed deer (Odocoileus virginianus) is the most important big game mammal in Mexico and North America. In Mexico there are 14 subspecies that are distributed throughout the country except in the peninsula of Baja California. As trophy big game, this cervid is recorded in several record books as: the Boone &amp; Crockett Club (B&amp;C) and the one of Safari Club International (SCI). The “texanus” and the “couesi” subspecies are the only ones which qualify for the B&amp;C. The SCI classifies four categories: two northern subspecies: “couesi” and the “texanus”, and two other categories; Mexican and Central American. Due to the above the more valued subspecies by the record books are the northern as texanus, carminis and couesi .As a result of this, there has been low demand for sport hunting and there are few records of the deer subspecies in central and southern Mexico. Therefore, in 2012 the SCI included seven new categories of big game trophies of that cervid, with the objective to revalue hunting these geographical races. Consequently, the regional distribution of the subspecies for Mexico was discussed to establish the new categorization at the regional, state and municipal level. The seven new categories are: Coues white-tailed deer, Carmen Mountains white-tailed deer, Mexican Texanus white-tailed deer, Mexican Pacific coast white-tailed deer, Mexican Central Plateau white-tailed deer, Mexican gulf coast white-tailed deer and Central America white-tailed deer. In addition the SCI chapter Monterrey established the Thummler Award in two categories: Gold and Diamond, which include among other Mexican deer species and subspecies, five and seven categories of white-tailed deer respectively. This regionalization, seeks to increase the sustainable use of trophy game in a more evenly way in the country, and that in the future these regions receive ecological, economic and social benefits.  El venado cola blanca (Odocoileus virginianus) es el mamífero de caza mayor más importante de México y Norteamérica. En México se existen 14 subespecies que se distribuyen en todo el país excepto en la península de Baja California. Como trofeo cinegético, este cérvido es registrado por medio de varios libros de records como: el Boone &amp; Crockett Club (B&amp;C) y el del Safari Club Internacional (SCI). El B&amp;C solo califican las subespecies “texanus” y la “couesi”. El SCI clasifica cuatro categorías: dos subespecies norteñas: “couesi” y el “texanus”, y otras dos categorías; mexicanos y centroamericanos. Debido a lo anterior las subespecies más valoradas por los libros de records son las norteñas como texanus, carminis y couesi .Como consecuencia, ha existido baja demanda para la caza deportiva y existen pocos registros de las subespecies del venado en centro y sur de México. Por lo tanto el SCI incluyó el año 2012 siete nuevas categorías de trofeos de caza de ese cérvido, con el objetivo revalorar cinegéticamente esas razas geográficas. Para lo cual, se analizó de la distribución regional de las subespecies para México, para de esta forma establecer la nueva categorización a nivel regional, estatal y municipal. Las siete nuevas categorías son: Venado cola blanca de Coues, Venado cola blanca de la Sierra del Carmen, Venado cola blanca Mexicano de Texas, Venado Cola Blanca Mexicano de la Costa del Pacífico, Venado cola blanca Mexicano del Altiplano; Venado cola blanca Mexicano de las costas del Golfo, y Venado cola blanca de América Central. Además el SCI capitulo Monterrey instituyo el Premio Thummler en dos categorías: Oro y Diamante, que incluyen entre otras especies y subespecies de cérvidos mexicanos, cinco y siete categorías de venado cola blanca respectivamente. Con esta regionalización, se busca incrementar el uso sustentable de trofeos de caza de forma más homogénea en el país, y que a futuro esas regiones reciban benéficos ecológicos, económicos y sociales

Formation of Pd2Si on single-crystalline Si (100) at ultrafast heating rates : an in-situ analysis by nanocalorimetry

The kinetics of intermediate phase formation between ultrathin films of Pd (12 nm) and single-crystalline Si (100) is monitored by in-situ nanocalorimetry at ultrafast heating rates. The heat capacity curves show an exothermic peak related to the formation of Pd2Si. A kinetic model which goes beyond the conventional linear-parabolic growth to consider independent nucleation and lateral growth of Pd2Si along the interface and vertical growth mechanisms is developed to fit the calorimetric curves. The model is used to extract the effective interfacial nucleation/growth and diffusion coefficients at the unusually high temperatures of silicide formation achieved at very fast heating rates