Optical amplification enhancement in photonic crystals

Improving and controlling the efficiency of a gain medium is one of the most challenging problems of laser research. By measuring the gain length in an opal based photonic crystal doped with laser dye, we demonstrate that optical amplification is more than twenty-fold enhanced along the Gamma-K symmetry directions of the face centered cubic photonic crystal. These results are theoretically explained by directional variations of the density of states, providing a quantitative connection between density of the states and light amplification

Environmental effects on the photophysics of organic-inorganic halide perovskites

The photophysical properties of films of organic-inorganic lead halide perovskites under different ambient conditions are herein reported. We demonstrate that their luminescent properties are determined by the interplay between photoinduced activation and darkening processes, which strongly depend on the atmosphere surrounding the samples. We have isolated oxygen and moisture as the key elements in each process, activation and darkening, both of which involve the interaction with photogenerated carriers. These findings show that environmental factors play a key role in the performance of lead halide perovskites as efficient luminescent materials.Peer Reviewe

Surface Electromyography of the Longissimus and Gluteus Medius Muscles in Greyhounds Walking and Trotting on Ground Flat, Up, and Downhill

In the field of canine rehabilitation, knowledge of muscle function in the therapeutic exercises prescribed is needed by physical therapists and veterinary surgeons. To gain insight into the function of longissimus dorsi (LD) and gluteus medius (GM) muscles in dogs, five Greyhounds performing leash walking and trotting on the ground flat, up (+7%), and downhill (−7%) were studied by surface electromyography, and the mean and maximum activity was compared. For the same incline, the surface electromyography (sEMG) of LD was higher (p < 0.05) at the trot than at the walk. In LD muscle, trotting uphill showed significantly higher maximum activity than any other exercise. A change of +7% incline or −7% decline affected (increased or decreased, respectively) the mean sEMG of the LD and GM muscles of dogs walking or trotting on the ground. When combined, the influence of gait and incline on electromyographic activity was analyzed, and walking at certain inclines showed no difference with trotting at certain inclines. Walking and trotting up and downhill added separate therapeutic value to flat motion. The results of the present study might contribute to a better understanding of the function of LD and GM muscles in dogs, this being especially useful for the field of canine rehabilitation

Overcharging: The Crucial Role of Excluded Volume

In this Letter we investigate the mechanism for overcharging of a single spherical colloid in the presence of aqueous salts within the framework of the primitive model by molecular dynamics (MD) simulations as well as integral-equation theory. We find that the occurrence and strength of overcharging strongly depends on the salt-ion size, and the available volume in the fluid. To understand the role of the excluded volume of the microions, we first consider an uncharged system. For a fixed bulk concentration we find that upon increasing the fluid particle size one strongly increases the local concentration nearby the colloidal surface and that the particles become laterally ordered. For a charged system the first surface layer is built up predominantly by strongly correlated counterions. We argue that this a key mechanism to produce overcharging with a low electrostatic coupling, and as a more practical consequence, to account for charge inversion with monovalent aqueous salt ions.Comment: 7 pages, 3 figs (4 EPS files). To appear in Europhysics Letter

Cellular Viscosity in Prokaryotes and Thermal Stability of Low Molecular Weight Biomolecules

8 páginas.-- 6 figuras.-- 32 referenciasSome low molecular weight biomolecules, i.e., NAD(P)H, are unstable at high temperatures. The use of these biomolecules by thermophilic microorganisms has been scarcely analyzed. Herein, NADH stability has been studied at different temperatures and viscosities. NADH decay increased at increasing temperatures. At increasing viscosities, NADH decay rates decreased. Thus, maintaining relatively high cellular viscosity in cells could result in increased stability of low molecular weight biomolecules (i.e., NADH) at high temperatures, unlike what was previously deduced from studies in diluted water solutions. Cellular viscosity was determined using a fluorescent molecular rotor in various prokaryotes covering the range from 10 to 100°C. Some mesophiles showed the capability of changing cellular viscosity depending on growth temperature. Thermophiles and extreme thermophiles presented a relatively high cellular viscosity, suggesting this strategy as a reasonable mechanism to thrive under these high temperatures. Results substantiate the capability of thermophiles and extreme thermophiles (growth range 50–80°C) to stabilize and use generally considered unstable, universal low molecular weight biomolecules. In addition, this study represents a first report, to our knowledge, on cellular viscosity measurements in prokaryotes and it shows the dependency of prokaryotic cellular viscosity on species and growth temperature.The authors acknowledge funding from projects No. CSD2009-0006 and No. CGL2014-58762-P from the Spanish Ministry of Economy and Competitiveness and grants No. BIO-288 and No. RNM2529 from the Andalusian Government. Federal funds cofinanced these projects. Funding from the mobility program No. 003-ABEL-CM-2013 (NILS Science and Sustainability program, EEA grants) is also acknowledged.Peer Reviewe

Variations in the basic biokinematic pattern in three breeds of horses at the hand-led walk

In this study the lineal and temporal parameters of the stride of andalusian (n=10), angloarabian (n=6) and arabian (n=7) mature horses were compared at the walk. The speeds were similar in the three breeds (1.63±0.10 m/s), for what the Archivos de zootecnia vol. 48, núm. 183, p. 328. GALISTEO ET AL. statistical comparisons were carried out by an analysis of the variance, and a means comparison test (Tukey test). The stride lenght was shorter in arabians and andalusians than in angloarabians, while the overtracking lenght was bigger in the arabians. The duration of the forelimb cycle was bigger in angloarabians due to a bigger duration in this breed of the stance phase. The midstace position (expressed as a percentaje of the stride duration) differed among the three breeds, indicating that each one shows times of braking and propulsion of the forelimb different to the other ones; but not in the instant in which the hoof reaches the highest point in its trajectory. In the hind limb the differences were much less marked, since small differences were detected in the duration of the cycle between arabians and angloarabians, while the stride duration was longer in andalusians and angloarabians than in the Arabians; the braking and propulsion phases (determined by the position along the stride of the midstance position) didn’t differ among breeds, the same with the instant in which the hindhoof reach the highest point in its trajectory. It can be concluded that marked differences exist between equine breeds in the lineal parameters of the stride at the walk, and the temporal parameters of the forelimb, while in the hind limb are less marked, probably because this member is functionally committed in the propulsion of the horse.En este estudio se compararon los parámetros lineales y temporales del tranco de paso de caballos adultos de Pura Raza Española (n=10), Angloárabe (n=6) y Árabe (n=7). Las velocidades fueron similares en las tres razas (1,63±0,10 m/s), por lo que las comparaciones estadísticas se realizaron mediante un análisis de la varianza y un test de comparación de medias (Test de Tukey). La amplitud de tranco fue más corta en Árabes y Españoles que en Angloárabes, mientras que la longitud de sobrehuella fue mayor en los Árabes. La duración del ciclo del miembro torácico fue mayor en Angloárabes debido a una mayor duración en esta raza de la fase de apoyo. La posición de apoyo medio (expresada porcentualmente a la duración total del ciclo) difirió entre las tres razas, indicando que cada raza presenta tiempos de frenada y propulsión del miembro torácico diferentes a las demás; no así en el instante en el que el casco alcanza el punto más alto de su trayectoria. En el miembro pelviano las diferencias fueron mucho menos marcadas, ya que se detectaron pequeñas diferencias en la duración del ciclo entre Árabes y Angloárabes, mientras que la duración del tranco fue mayor en Españoles y Angloárabes que en los Árabes; los tiempos de frenada y propulsión (determinada por la posición a lo largo del tranco del apoyo medio) no difirió entre razas, lo mismo que el instante en que el casco pelviano se encuentra en el punto más alto de su trayectoria. Se puede concluir que existen marcadas diferencias entre razas equinas en los parámetros lineales del tranco al paso, al igual que sucede con los parámetros temporales del miembro torácico, mientras que en el pelviano son menos marcadas, probablemente porque este miembro está funcionalmente más comprometido que el torácico en la propulsión del caballo

Bioinspired Synthesis of Platensimycin from Natural ent-Kaurenoic Acids

Ministerio de Economía y Competitividad, PID2019-106222RB-C32/SRA (State Research Agency, 10.13039/501100011033)Universidad de Granada/CBU

Unexpected Optical Blue Shift in Large Colloidal Quantum Dots by Anionic Migration and Exchange

Compositional changes taking place during the synthesis of alloyed CdSeZnS nanocrystals (NCs) allow shifting of the optical features to higher energy as the NCs grow. Under certain synthetic conditions, the effect of those changes on the surface/interface chemistry competes with and dominates over the conventional quantum confinement effect in growing NCs. These changes, identified by means of complementary advanced spectroscopic techniques such as XPS (X-ray photoelectron spectroscopy) and XAS (X-ray absorption spectroscopy), are understood in the frame of an ion migration and exchange mechanism taking place during the synthesis. Control over the synthetic routes during NC growth represents an alternative tool to tune the optical properties of colloidal quantum dots, broadening the versatility of the wet chemical methods.Fil: Acebrón, María. IMDEA Nanociencia; EspañaFil: Galisteo López, Juan F.. Universidad de Sevilla. Consejo Superior de Investigaciones Cientificas. Instituto de Ciencia de Materiales de Sevilla; EspañaFil: López, Cefe. Instituto de Ciencia de Materiales de Madrid; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Herrera, Facundo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Mizrahi, Martin Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Requejo, Felix Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Palomares, F. Javier. Consejo Superior de Investigaciones Científicas; España. Instituto de Ciencia de Materiales de Madrid; EspañaFil: Juárez, Beatriz H.. Universidad Autónoma de Madrid; España. IMDEA Nanoscience; Españ

The hydrogen–air burning rate near the lean flammability limit

This paper investigates the inner structure of the thin reactive layer of hydrogen–air fuellean deflagrations close to the flammability limit. The analysis, which employs seven elementary reactions for the chemistry description, uses the ratio of the characteristic radical and fuel concentrations as a small asymptotic parameter, enabling an accurate analytic expression for the resulting burning rate to be derived. The analysis reveals that the steady-state assumption for chemical intermediaries, applicable on the hot side of the reactive layer, fails, however, as the crossover temperature is approached, providing a nonnegligible higher-order correction to the burning rate. The results can be useful, for instance, in future investigations of hydrogen deflagration instabilities near the lean flammability limit

Genetic parameters of biokinematic variables of the trot in Spanish Purebred horses under experimental treadmill conditions

The purpose of this study was to estimate the genetic parameters of biokinematic variables in Spanish Purebred (SPB) horses in order to select those of sufficient interest to be measured in the pre-selection of the animals for possible inclusion in the breeding programme. Kinematic analysis of 130 SPB horses 4.6 ± 1.5 years old were recorded at the trot (4 m/s) on a treadmill. Genetic parameters were estimated using VCE software and a bivariate mixed animal model including age and stud as fixed effects and animal additive genetic effect and residual error as random effects. In general, heritabilities were high (0.33–0.88). The angular variables presented the lowest heritabilities, whereas the maximum height of the fore-hoof and the duration of swing phase in the hindlimb gave the highest scores. Genetic correlations were also very high, so it was possible to reduce the number of breeding programme characteristics to stride duration, hindlimb swing phase duration, range of stifle and elbow angles, minimal angle of carpus, and minimal retraction-protraction angle of the hindlimb.Unión Europea 1FD97-089