Desarrollo de técnicas láser para aplicaciones en nanotecnología

Describe la importancia de las técnicas láser para el desarrollo de aplicaciones en nanotecnología. Define, además, los tipos de láseres según el medio activo y el funcionamiento de los mismos

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

Expanded use of a fast photography technique to characterize laser-induced plasma plumes

Expanded use of fast photography is proposed to characterize laser ablation plasma plumes by the analysis of a set of photographs by means of appropriate mathematical algorithms. The laser ablation plasma plumes studied were generated by ablation of both a multicomponent target of the nominal composition Ni50Mn37Sn13 and a highly pure Cu target (Cu) using a Q-switched Nd-YAG laser system:The experiments were conducted under different background argon pressures. Several photograph parameters such as intensity per unit time of exposure for a pixel, mean intensity per pixel per unit time of exposure, integrated intensity and cross correlation were studied. The intensity per unit time of exposure allowed for identification of the fast component of the triple structure of the expanding plasma into the background gas (that travels at a speed close to the one measured in vacuum). This parameter together with the use of cross correlation enabled the identification of regions of the expanded plasma plume with higher and lower similarities in their optical emission behavior. The mean intensity per pixel per unit time of exposure can be used as a measurement of the amount of light emitted by the plume as a function of time

Efecto del campo magnético en la síntesis de nanopartículas de oro y plata coloidal por ablación láser en agua bidestilada

The effect of magnetic field of 0.3 T on the concentration, distribution of sizes in suspension and zeta potential of colloidal gold and colloidal silver nanoparticles, obtained by considering the pulsed laser ablation in double distilled water was studied. The magnetic field was transverse to the direction of incidence of the laser radiation and parallel to the surface of a submerged target. An Nd: YAG laser was used (1064 nm in wavelength, 10 ns in duration, repetition rate of 10 Hz and 37 mJ of energy) to ablate targets. The colloids were characterized by inductively coupled plasma optical emission spectroscopy, ultraviolet-visible spectroscopy, dynamic light scattering and zeta potential. Concentration analysis suggested that applying magnetic field of 0.3 T during nanoparticle synthesis leads to higher concentration. Applying magnetic field led to an eleven percent increase in the concentration of the colloid with gold nanoparticles and a five percent increase in the concentration of the colloidal silver nanoparticles. The absorption spectra suggested the presence of spherical nanoparticles. When analyzing the effect of the magnetic field on the hydrodynamic size distribution of the nanoparticles and the zeta potential of the colloids, no significant changes were evidenced. The magnetic confinement of the plasma induced by laser ablation caused changes in the characteristics of the colloids.Se estudió el efecto del campo magnético (0.3 T) sobre la concentración, distribución de tamaños en suspensión y potencial zeta de nanopartículas coloidales de oro y plata, obtenidas al considerar la técnica de ablación láser pulsada en agua bidestilada. El campo magnético fue transversal a la dirección de incidencia de la radiación láser y paralelo a la superficie del blanco sumergido. Se utilizó un láser Nd:YAG, emitiendo pulsos de 1064 nm de longitud de onda, 10 ns de duración, razón de repetición de 10 Hz y 37 mJ de energía. Los coloides fueron caracterizados al considerar las técnicas: espectroscopia de emisión por plasma de acoplamiento inductivo, espectroscopia ultravioleta-visible, esparcimiento dinámico de luz y potencial zeta. Los análisis de concentración demostraron que aplicar campo magnético de 0.3 T durante la síntesis de nanopartículas conlleva a obtener mayor concentración. Aplicar campo magnético conllevó a incrementar en once por ciento la concentración del coloide con nanopartículas de oro y en cinco por ciento la concentración del coloide con nanopartículas de plata. Los espectros de absorción obtenidos son característicos de nanopartículas esféricas. Al analizar el efecto del campo magnético en la distribución de tamaños hidrodinámicos de las nanopartículas y en el potencial zeta, no se evidenció cambios significativos. El confinamiento magnético del plasma inducido por ablación láser ocasionó cambios en las características de los coloides

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

International audienceIn 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field