Production of nanometer-size GaAs nanocristals by nanosecond laser ablation in liquid.

This paper reports the formation and characterization of spherical GaAs quantum dots obtained by nanosecond pulsed laser ablation in a liquid (ethanol or methanol). The produced bare GaAs nanoparticles demonstrate rather narrow size distribution which depends on the applied laser power density (from 4.25 to 13.9 J/cm2 in our experiments) and is as low as 2.5 nm for the highest power used. The absolute value of the average diameter also decreases significantly, from 13.7 to 8.7 nm, as the laser power increases in this interval. Due to the narrow nanoparticle size dispersion achieved at the highest laser powers two absorption band edges are clearly distinguishable at about 1.72 and 3.15 eV which are ascribed to E0 and E1 effective optical transitions, respectively. A comparison of the energies with those known for bulk GaAs allows one to conclude that an average diameter of the investigated GaAs nanoparticles is close to 10 nm, i.e., they are quantum dots. High resolution transmission electron microscopy (HRTEM) images show that the bare GaAs nanoparticles are nanocrystalline, but many of them exhibit single/multiple twin boundary defects or even polycrystallinity. The formation of the GaAs crystalline core capped with a SiO2 shell was demonstrated by HRTEM and energy dispersive X-ray (EDX) spectroscopy. Effective band edges can be better distinguished in SiO2 capped nanoparticles than in bare ones, In both cases the band edges are correlated with size quantum confinement effect.

Observational Analysis of Lateral Preference in Kumite Initiation: A Starting Point in the Longitudinal Programming of Formative Karate.

We used observational methodology to analyze lateral conditioning in the technical-tactical performance of high level 8-9-year-old karatekas, specifically in relation to the guard action that supports the technical action and the body segment with which it is performed. We designed an ad hoc observation instrument to analyze lateral preference in the technical-tactical actions that take place during the kumite. We relied on LINCE software for data registration, and we found good inter-observer reliability, calculated with Cohen's Kappa coefficient. Generalizability Theory supported the homogeneity of the behavior deployed by these combatants. Our results represent a starting point in the longitudinal programming of karate. By relating our results and those of other studies that have addressed lateral performance in formative karate in the kumite modality, we are able to draw a roadmap of a karateka's path towards the equilaterality that is inherent in an elite competitor: (a) the 8-9 year old karateka must overcome a conditioned lateral prevalence by adopting a forward non-dominant leg guard so as to then attack with the dominant body segment; (b) the eqilateral use of the right or left fist must occur later, between the 12-13 year age group and the senior category; and (c) there will then be less decisive lateral conditioning in the execution of offensive leg techniques.

Evaluation of the release of nickel and titanium under orthodontic treatment.

The metal alloys used in dentistry are made mainly of nickel (Ni), titanium (Ti), and other elements such as molybdenum (Mo), zirconium (Zr), iron (Fe), tin (Sn), chrome (Cr), carbon (C), copper (Cu) and niobium (Nb) which can release metal ions in unstable environments. The aim of this work was determine the salivary pH before and during orthodontic treatment; evaluate the release of metal ions, mainly Ni and Ti, in urine and saliva using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES); and evaluate the corrosion using Scanning Electronic Microscopy (SEM). In this study, we selected 35 individuals under orthodontic treatment, from whom saliva and urine samples were collected in 3 stages: (a) basal, (b) at 3 and (c) 6 months after the placement of the fixed appliances. SEM analyzed the Ni-Ti (0.016″) and stainless steel (SS) (0.016 × 0.022″) archs after 1 month of being in contact with the oral cavity. Statistical analysis was performed with Stata using the ANOVA model of repeated measures with a p < 0.05. A statistically significant difference in the concentration of Ni in saliva were found between 3 and 6 months of intervention and Ti in urine was found 3 and 6 months.

Soil emissivity and reflectance spectra measurements.

We present an analysis of the laboratory reflectance and emissivity spectra of 11 soil samples collected on different field campaigns carried out over a diverse suite of test sites in Europe, North Africa, and South America from 2002 to 2008. Hemispherical reflectance spectra were measured from 2.0 to 14 microm with a Fourier transform infrared spectrometer, and x-ray diffraction analysis (XRD) was used to determine the mineralogical phases of the soil samples. Emissivity spectra were obtained from the hemispherical reflectance measurements using Kirchhoff's law and compared with in situ radiance measurements obtained with a CIMEL Electronique CE312-2 thermal radiometer and converted to emissivity using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and emissivity separation algorithm. The CIMEL has five narrow bands at approximately the same positions as the ASTER. Results show a root mean square error typically below 0.015 between laboratory emissivity measurements and emissivity measurements derived from the field radiometer.

Relaxant action of androgens, progestins and corticosteroids on the isolated ileum of the guinea pig

La acción de tres diferentes clases de derivados de la progesterona fueron probados sobre las contracciones espontáneas del íleon aislado de cobayo. Los resultados mostraron que este tejido es muy sensible a la acción de los esteroides. Se observó una marcada relajación que fue dependiente de la dosis y diferente para cada compuesto. Esta diferencia fue asociada a la estructura molecular del esteroide. Así, las progestinas 5ß-reducidas fueron las más potentes, seguidas de los andrógenos 5 alfa y 5ß-reducidos. Los compuestos 4-en, 17 alfa-OH-progesterona y los corticosteroides, fueron los más bajos en potencia. La 5alfa-pregnandiona y los pregnandioles fueron prácticamente inefectivos. La gran sensibilidad del músculo liso del íleon permite postular a este órgano como blanco de esteroides. Es posible que en algunas circunstancias fisiológicas, como podría ser el embarazo, los trastornos de motilidad intestinal observados en este estado estén asociados al incremento notable de esteroides circulantes (AU)

Relaxant action of androgens, progestins and corticosteroids on the isolated ileum of the guinea pig

La acción de tres diferentes clases de derivados de la progesterona fueron probados sobre las contracciones espontáneas del íleon aislado de cobayo. Los resultados mostraron que este tejido es muy sensible a la acción de los esteroides. Se observó una marcada relajación que fue dependiente de la dosis y diferente para cada compuesto. Esta diferencia fue asociada a la estructura molecular del esteroide. Así, las progestinas 5ß-reducidas fueron las más potentes, seguidas de los andrógenos 5 alfa y 5ß-reducidos. Los compuestos 4-en, 17 alfa-OH-progesterona y los corticosteroides, fueron los más bajos en potencia. La 5alfa-pregnandiona y los pregnandioles fueron prácticamente inefectivos. La gran sensibilidad del músculo liso del íleon permite postular a este órgano como blanco de esteroides. Es posible que en algunas circunstancias fisiológicas, como podría ser el embarazo, los trastornos de motilidad intestinal observados en este estado estén asociados al incremento notable de esteroides circulantes