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Domestication of small-seeded lima bean (Phaseolus lunatus L.) landraces in Mesoamerica: evidence from microsatellite markers

RUBEN HUMBERTO ANDUEZA NOH JAIME MARTINEZ CASTILLO MARÍA ISABEL CHACÓN SÁNCHEZ (2015)

Previous studies have suggested that the Mesoamerican small-seeded landraces of Lima bean may have been domesticated more than once in Mesoamerica, once in central-western Mexico and another one in an area between Guatemala and Costa Rica. However, these findings were based on sequencing of only one locus from nuclear DNA, and additional confirmation was needed. Here we contribute with additional data on the origin of the Mesoamerican landraces and document the founder effect due to domestication. We characterized 62 domesticated, 87 wild and six weedy Lima bean accessions with ten microsatellite loci. Genetic relationships were analyzed using genetic distances and Bayesian clustering approaches. Domestication bottlenecks were documented using inter-population comparisons and M ratios. The results support at least one domestication event in the area of distribution of gene pool MI in central-western Mexico and also show that some landraces are genetically related to wild accessions of gene pool MII. Also, our data support founder effects due to domestication in Mesoamerican Lima bean landraces. Although we could not establish more specifically the place of origin of the Mesoamerican Lima bean landraces, our results show that these are not a genetically homogeneous group, a finding that may be compatible with a scenario of more than one domestication event accompanied by gene flow. The complex genetic makeup of landraces that we found indicates that a more comprehensive geographic and genomic sampling is needed in order to establish how domestication processes and gene flow have shaped the current genetic structure of landraces.

Article

BAYESIAN CLUSTERING CROP DOMESTICATION FOUNDER EFFECT GENETIC DISTANCE SSR MARKERS WILD ANCESTORS BIOLOGÍA Y QUÍMICA

Development of a large set of microsatellite markers in zapote mamey (Pouteria sapota (Jacq.) H.E. Moore

&

Stearn) and their potential use in the study of the species

JAIME MARTINEZ CASTILLO NASIB HIRAM BLANCARTE JASSO (2015)

Pouteria sapota is known for its edible fruits that contain unique carotenoids, as well as for its fungitoxic, anti-inflammatory and anti-oxidant activity. However, its genetics is mostly unknown, including aspects about its genetic diversity and domestication process. We did high-throughput sequencing of microsatellite-enriched libraries of P. sapota, generated 5223 contig DNA sequences, 1.8 Mbp, developed 368 microsatellites markers and tested them on 29 individuals from 10 populations (seven wild, three cultivated) from Mexico, its putative domestication center. Gene ontology BLAST analysis of the DNA sequences containing microsatellites showed potential association to physiological functions. Genetic diversity was slightly higher in cultivated than in the wild gene pool (HE = 0.41 and HE = 0.35, respectively), although modified Garza-Williamson Index and Bottleneck software showed evidence for a reduction in genetic diversity for the cultivated one. Neighbor Joining, 3D Principal Coordinates Analysis and assignment tests grouped most individuals according to their geographic origin but no clear separation was observed between wild or cultivated gene pools due to, perhaps, the existence of several admixed populations. The developed microsatellites have a great potential in genetic population and domestication studies of P. sapota but additional sampling will be necessary to better understand how the domestication process has impacted the genetic diversity of this fruit crop.

Article

BLAST ANALYSIS FOUNDER EFFECT GENETIC DIVERSITY GERMPLASM DOMESTICATION BIOLOGÍA Y QUÍMICA

Domestication of small-seeded lima bean (Phaseolus lunatus L.) landraces in Mesoamerica: evidence from microsatellite markers

RUBEN HUMBERTO ANDUEZA NOH JAIME MARTINEZ CASTILLO MARÍA ISABEL CHACÓN SÁNCHEZ (2015)

Previous studies have suggested that the Mesoamerican small-seeded landraces of Lima bean may have been domesticated more than once in Mesoamerica, once in central-western Mexico and another one in an area between Guatemala and Costa Rica. However, these findings were based on sequencing of only one locus from nuclear DNA, and additional confirmation was needed. Here we contribute with additional data on the origin of the Mesoamerican landraces and document the founder effect due to domestication. We characterized 62 domesticated, 87 wild and six weedy Lima bean accessions with ten microsatellite loci. Genetic relationships were analyzed using genetic distances and Bayesian clustering approaches. Domestication bottlenecks were documented using inter-population comparisons and M ratios. The results support at least one domestication event in the area of distribution of gene pool MI in central-western Mexico and also show that some landraces are genetically related to wild accessions of gene pool MII. Also, our data support founder effects due to domestication in Mesoamerican Lima bean landraces. Although we could not establish more specifically the place of origin of the Mesoamerican Lima bean landraces, our results show that these are not a genetically homogeneous group, a finding that may be compatible with a scenario of more than one domestication event accompanied by gene flow. The complex genetic makeup of landraces that we found indicates that a more comprehensive geographic and genomic sampling is needed in order to establish how domestication processes and gene flow have shaped the current genetic structure of landraces.

Article

BAYESIAN CLUSTERING CROP DOMESTICATION FOUNDER EFFECT GENETIC DISTANCE SSR MARKERS WILD ANCESTORS BIOLOGÍA Y QUÍMICA BIOLOGÍA Y QUÍMICA

Efecto del viroide de la mancha de sol en el rendimiento y calidad de frutos en aguacate de Michoacán

JOSE RAMON SAUCEDO CARABEZ (2013)

Tesis (Maestría en Ciencias, especialista en Fitopatología).- Colegio de Postgraduados, 2013.

Avocado sunblotch viroid (ASBVd) es una enfermedad considerada de importancia económica que se reportó en México en 2009. El objetivo del presente trabajo fue evaluar el efecto del ASBVd en el rendimiento y calidad de frutos en aguacate de Michoacán debido a la importancia de la enfermedad y del cultivo. Cuatro árboles sanos fueron comparados con cuatro asintomáticos y cuatro sintomáticos del cultivar ‘Hass’ y de la selección ‘Méndez’ en 2 huertos con diferente manejo. En campo se registró el rendimiento total de los árboles. En cada árbol se midió el peso, diámetro ecuatorial (DE), diámetro polar (DP) de 100 frutos y la incidencia de frutos con síntomas. Frutos ‘Hass’ de cinco condiciones: Frutos sanos de árboles sanos (C1), frutos sanos de árboles asintomáticos (C2), frutos sanos de árboles sintomáticos (C3), frutos sintomáticos con severidad clase 1 (C4), frutos con severidad clase 2 (C5) se cosecharon en 2011 y 2012 para evaluar las variables de cambio de coloración, firmeza, pérdida de peso y el contenido mineral en etapa de madurez fisiológica y comercial. El peso total en frutos ‘Hass’ con síntomas fue reducido en más del 50 % y mayor al 75 % en ‘Méndez’ en ambos huertos, mientras que los asintomáticos hubo una reducción mayor en ‘Méndez’ con un 58 % y 30 % en ‘Hass’. Las variables de peso en 100 frutos, DP y DE fueron estadísticamente menores en árboles sintomáticos con respecto a árboles sanos y asintomáticos. La incidencia de frutos ‘Hass’ con síntomas fue mayor a 45 % y mayor a 20 % en ‘Méndez’. C1, C2 y C3 maduraron de manera uniforme y no mostraron diferencias significativas en ninguna de las variables evaluadas, mientras que C4 y C5 presentaron una maduración irregular, relacionada a una firmeza y cambio de coloración más lento con una pérdida de peso menor. El contenido mineral no presentó ninguna diferencia significativa en ninguna de las dos etapas. _______________ ABSTRACT: The effect of Avocado sunblotch viroid (ASBVd) was evaluated in four healthy, four asymptomatic (molecularly positive), and four symptomatic trees of cv. Hass (Persea americana) and Mendez in grove 1 in Uruapan County. Four healthy and four symptomatic trees were evaluated in grove 2 in Tingambato County. The total Hass fruit weight from symptomatic trees was significantly (75 %) reduced (213 vs 751 kg from healthy trees) in grove 1 and 52 % (124 vs 255 kg) in grove 2 (Tukey, p=0.05). This reduction was more severe in Mendez, 83 % in grove 1 (183 vs 1,053 kg) and 76 % in grove 2 (82 vs 340 kg). Yield of asymptomatic trees was 58 % reduced in Mendez and 30 % in Hass. The average weight of 100 fruits was 13-28 % reduced in Hass and 20-27 % in Mendez in groves 2 and 1 respectively. The equatorial diameter of 100 symptomatic fruits was 8 % lower in Hass in both groves, and 20-28 % in Mendez. The polar diameter decreased by 8-10 % in Hass and 10-11 % in Mendez. The incidence of symptomatic fruits was 46-62 % in Hass and 20-28 % in Mendez. Yield of ASBVd symptomatic Hass and Mendez tress was significantly reduced and fruit morphology was negatively affected. Hass fruits (Persea americana) from five classes: healthy from healthy trees (C1), asymptomatic from asymptomatic trees (C2), asymptomatic from symptomatic trees (C3), symptomatic severity class 1 (C4), symptomatic severity class 2 (C5) were harvested in 2011 and 2012. ASBVd effect of on postharvest quality was evaluated by measuring the firmness, colour, weight loss, dry matter, mineral and oil content. C4 and C5 were significantly different (Tukey, p=0.05) in longer firmness, less dark coloration and less weight loss compared to C1, C2 and C3. Firmness in C4 and C5 was Ready To Eat (RTE) and not Soft (Soft) on the eighth day, while C1, C2 and C3 reached on the sixth day. Coloration in C1, C2 and C3 was black on the eighth day, whereas in C4 and C5 remained 75 % obscure. Weight loss in C4 and C5 was 1.4 g/day and C1, C2 and C3 was 2 g/day. Dry matter, mineral and oil content were similar in the five classes. ASBVd affected postharvest quality of symptomatic fruits. Asymptomatic fruits satisfy the international quality standards.

Master thesis

ASBVd Efecto Rendimiento Calidad Pérdida Incidencia Effect Yield Quality Loss Incidence Fitopatología Maestría CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Estrategia socio sexual y farmacológica para restablecer la actividad ovárica postparto en ovejas de pelo.

SILVIA FRAIRE CORDERO (2015)

Tesis (Doctorado en Ciencias, especialista en Ganadería).- Colegio de Postgraduados, 2015.

Se realizaron tres estudios para determinar la respuesta reproductiva y productiva postparto de ovejas de pelo al uso de “efecto macho” y a un protocolo de inducción del estro con la aplicación de un reconstituyente metabólico (R; Metabolice®) y Somatotropina bovina recombinante (rBST; Boostin-S®). En el primer estudio, 120 hembras y sus corderos, fueron asignados al azar a T1: Amamantamiento continuo (AC; n = 29), T2: AC+R (n = 29), T3: AC+Efecto Macho (EM; n = 32) y T4: AC+R+EM (n = 30). En el segundo, 94 hembras y sus corderos fueron asignados al azar a T1: AC (n = 29), T2: AC+R (n = 29), T3: AC+rBST (n = 17) y T4: R+rBST (n = 19). En el tercero, 97 hembras y sus corderos fueron asignados al azar a T1: AC (n = 29), T2: AC+EM (n = 32), T3: AC+rBST (n = 17) y T4: AC+EM+rBST (T4; n = 19). Se observó el porcentaje de ovulación a los 29 y 50 días postparto, cambios de peso en ovejas y corderos, incidencia e inicio del estro, retorno, fertilidad, gestación, parición, fecundidad y prolificidad. Para el primer estudio, el porcentaje de ovulación a los 29 días fue mayor para T3 y T4. Los cambios de peso en ovejas y corderos fueron diferentes en los periodos. El inicio del estro fue menor para T1 y T2. Gestación y parición fue mayor para T2. Para el estudio dos, el porcentaje de ovulación a los 29 días fue mayor para T4. A los 50 días fue mayor T1 y T2. El cambio de peso corporal fue diferente para tratamientos en corderos y periodo e interacción tratamiento por periodo en ovejas y corderos. T3 fue menor para incidencia, inicio del estro y fertilidad, pero mayor para retorno. T2 fue mayor para gestación, parición y fecundidad. Para el estudio tres, los mayores porcentajes de ovulación a los 29 días fueron para T2 y T4. A los 50 días, fueron mayores y similares T1, T2 y T4. El cambio de peso corporal fue diferente para tratamientos en corderos y periodo e interacción tratamiento por periodo en ovejas y corderos. Para incidencia y fecundidad T3 fue menor. El inicio del estro fue igual y menor para T1 y T4. El “efecto macho” durante 25 días influyó para restablecer la actividad ovárica de las ovejas en anestro postparto antes de los 29 días. El uso de un reconstituyente metabólico, puede utilizarse para mejorar la eficiencia reproductiva de las ovejas dentro de un protocolo de inducción del estro por cinco días, sin afectar los pesos de ovejas y corderos. La aplicación de rBST en general afecta las variables reproductivas y el peso corporal de las ovejas, pero mejora el peso corporal de los corderos. _______________ STRATEGY SOCIO SEXUAL AND PHARMACOLOGICAL TO RESTORE OVARIAN ACTIVITY POSTPARTUM IN HAIR SHEEP. ABSTRACT: Three studies were conducted to determine the postpartum reproductive and productive response of hair sheep to the use of " male effect " and a protocol for induction of estrus with the implementation of a metabolic tonic ( R; Metabolase® ) and recombinant bovine somatotropin ( rBST ; BOOSTIN - S® ). In the first study , 120 females and their lambs were randomly assigned to T1: continuous suckling ( AC ; n = 29 ) , T2 : AC + R ( n = 29 ) , T3 : AC + Effect Male ( EM ; n = 32 ) and T4 : AC + R + MS ( n = 30) . In the second, 94 females and their lambs were randomly assigned to T1 : AC ( n = 29 ) , T2 : AC + R ( n = 29 ) , T3 : AC + rBST ( n = 17) and T4 : R + rBST ( n = 19) . In the third, 97 females and their lambs were randomly assigned to T1 : AC ( n = 29 ) , T2 : AC + MS ( n = 32 ) , T3 : AC + rBST ( n = 17) and T4 : AC + EM + rBST ( T4 ; n = 19). The ovulation rate was observed at 29 and 50 days postpartum weight changes in sheep and lambs, incidence and onset of estrus, return, fertility, gestation, parturition, fecundity and prolificacy. For the first study, the percentage of ovulation at 29 days was greater for T3 and T4. Weight changes in sheep and lambs were different in periods. The estrus was reduced to T1 and T2. Pregnancy and calving was higher for T2. For the study two, the ovulation rate at 29 days was higher for T4. At 50 days was higher T1 and T2. The body weight change was different in lambs and treatment period and interaction treatment period in sheep and lambs. T3 was lower for incidence, onset of estrus and fertility, but more to return. T2 was higher for pregnancy, calving and fecundity. For the study three, the highest percentages of ovulation at 29 days were for T2 and T4. At 50 days, they were higher and similar T1, T2 and T4. The body weight change was different in lambs and treatment period and interaction treatment period in sheep and lambs. For incidence and fecundity T3 was lower. The estrus was equal and lower for T1 and T4. The "male effect" for 25 days influenced to restore ovarian activity in postpartum anoestrus sheep before 29 days. Using a metabolic tonic, it can be used to improve reproductive efficiency of sheep within a protocol of induction of estrus for five days, without affecting the weights of sheep and lambs. The application of rBST generally affects reproductive variables and body weight of the sheep, but improves the body weight of the lambs.

Doctoral thesis

Postparto Efecto macho Somatotropina Reconstituyente Postpartum Male effect Somatotropin Restorative Ganadería Doctorado CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS PRODUCCIÓN ANIMAL OVINOS

Manejo reproductivo postparto en ovejas de pelo

PAULINA PAOLA CASTILLO MALDONADO (2012)

Tesis (Maestría en Ciencias, especialista en Ganadería).- Colegio de Postgraduados, 2012.

En este estudio se evaluó el efecto del amamantamiento y un protocolo de sincronización postparto (PP) con el efecto del carnero y destete temporal en la respuesta reproductiva de las ovejas de pelo. Aisladas de los carneros dos meses antes de la sincronización, 96 ovejas fueron clasificadas aleatoriamente al parto en dos grupos (n=48): amamantamiento continuo por 18 horas (Ac) y lactancia controlada con amamantamiento por 30 min 2 veces día-1 (Lc). En el día 35 PP las ovejas se sincronizaron con CIDR por 10 días; y 48 horas antes de retirarlo se les aplicó 7.5 mg de dinoprost y se probó el efecto del carnero (Ca) y el destete temporal (Dt). Se determinó el contenido de progesterona plasmática (P4) por RIA a los 30, 35, 50, 55 y 64 días PP. Las ovejas fueron inseminadas vía intrauterina con laparoscopio abdominal 12 a 15 horas después de iniciado el estro. Las variables de respuesta fueron: porcentaje de ovulación antes de los 35 días PP, hora de inicio del estro, tasa de gestación, prolificidad y pesos de las ovejas y de sus crías. La información obtenida fue analizada mediante regresión logística y de Poisson, prueba de Chi cuadrada, curvas de supervivencia y análisis de medidas repetidas. El porcentaje de ovejas que ovularon antes de los 35 días PP fue mayor (p<0.05) en Lc (89.6 %) con respecto a Ac (52.1 %). El peso de las ovejas fue similar (p>0.05) entre tratamientos. El peso de los corderos fue mayor (p<0.05) en Ac a partir de los 41 días PP y no hubo mortalidad durante la lactancia. Después del retiro del CIDR todas las ovejas manifestaron estro, siendo las de Lc (p<0.05) las que entraron antes (a las 50 horas). La tasa de gestación, prolificidad y fecundidad no fueron diferentes entre tratamientos y el promedio fue de 82.3%, 1.84 y 1.51 corderos, respectivamente. Los resultados muestran que al controlar la lactancia se aumenta y concentra el número de ovejas que ovularon antes de los 35 días PP, y que la ganancia de peso de los corderos disminuye después de los 41 días PP. Todas las ovejas respondieron a la sincronización postparto y al efecto del carnero al manifestar comportamiento estral, con buenas posibilidades de quedar gestantes, ya que solo una oveja presentó un cuerpo lúteo de vida media corta. _______________ POSTPARTUM REPRODUCTIVE MANAGEMENT IN HAIR SHEEPS. ABSTRACT: The purpose of this study was to determine the effect of suckling and postpartum (PP) synchronization protocol with the effect of the ram and temporary weaning on reproductive performance of hair sheep. Isolated from the rams two months before synchronization, 96 ewes were randomly assigned to one of two groups at lambing (n=48): continuous suckling for 18 h (Ac) and controlled suckling for 30 minutes twice a day (Lc). On day 35 PP, both groups were synchronized with CIDR for 10 days; 48 hours before CIDR removal 7.5 mg of dinoprost was administered and the effect of the ram (Ca) and the temporary weaning (Dt) were tested. We determined progesterone (P4) por radioimmunoassay at 30, 35, 50, 55 y 64 days PP. The ewes were inseminated intrauterine with abdominal laparoscope 12 to 15 hours after estrus onset. The response variables were: percentage of ovulation before 35 days PP, time of estrus onset, pregnancy rate, prolificacy and weight of ewes and their lambs. The information obtained was analyzed using logistic regression and Poisson, chi-square test, survival curves and repeated measures analysis. The percentage of ewes that ovulated before 35 days PP was higher (p<0.05) in Lc (89.6%) than Ac (52.1%). The weight of the sheep was similar (p> 0.05) between treatments. The weight of lambs was higher (p <0.05) in Ac after 41 days PP and there was no mortality during lactation. After CIDR removal all ewes showed estrus, being those of Lc (p <0.05) the first to manifest estrous behavior (50 hours). Pregnancy rate, prolificacy and fecundity were not different between treatments and averaged 82.3%, 1.84 and 1.51 lambs, respectively. The results indicate that controlling lactation increases and concentrates the number of ewes that ovulated before 35 days PP, and weight gain of the controlled lactation lambs decreases after 41 days PP. All ewes responded to the synchronization postpartum and the effect of ram to manifest estrous behavior, with good opportunities of becoming pregnant because only one ewe presented corpora lutea of shortened lifespan.

Master thesis

Efecto del carnero Tiempo de amamantamiento Destete temporal CIDR Corderos Progesterona RIA Ram effect Lambs Progesterone Hair ewes Ganadería Maestría Temporary weaning Postpartum lambs CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Effect of graphene oxide on bacteria and peripheral blood mononuclear cells

Jessica Rosaura Campos Delgado José Gil Munguía López Benjamin Fragneaud Joyce Araujo Francisco Gonzalez HUGO RICARDO NAVARRO CONTRERAS IVAN NELINHO PEREZ MALDONADO Antonio de León Rodríguez (2016)

"Background Driven by the potential biological applications of graphene, many groups have studied the response of cells exposed to graphene oxide (GO). In particular, investigations of bacteria indicate that there are 2 crucial parameters, which so far have only been investigated separately: GO size and exposure methodology. Our study took into account both parameters. We carefully characterized the samples to catalog sizes and structural properties, and tested different exposure methodologies: exposure in saline solution and in the presence of growth media. Furthermore, we performed experiments with peripheral blood mononuclear cells exposed to our GO materials. Methods Atomic force microscopy, scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy were used to characterize the morphology and composition of different samples of GO: GO-H2O, GO-PBS and GO-MG. Our samples had 2D sizes of ?100 nm (GO-H2O and GO-PBS) and >2 µm (GO-MG). We tested antibacterial activity and cytotoxicity toward peripheral blood mononuclear cells of 3 different GO samples. Results A size-dependent growth inhibition of Escherichia coli (DH5 ?) in suspension was found, which proved that this effect depends strongly on the protocol followed for exposure. Hemocompatibility was confirmed by exposing peripheral blood mononuclear cells to materials for 24 hours; viability and apoptosis tests were also carried out. Conclusions Our experiments provide vital information for future applications of GO in suspension. If its antibacterial properties are to be potentiated, care should be taken to select 2D sizes in the micrometer range, and exposure should not be carried out in the presence of grow media."

Article

Antibacterial effect Escherichia coli Graphene oxide Peripheral blood mononuclear cells BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOFÍSICA BIOFÍSICA

Transformation behavior and magnetocaloric effect in Mn1−xCrxCoGe (x = 0.04 and 0.11) melt-spun ribbons tailored by heat treatment

GERARDO DANIEL PÉREZ JOSE LUIS SANCHEZ LLAMAZARES Pablo Álvarez-Alonso CESAR FIDEL SANCHEZ VALDES ARIS QUINTANA NEDELCOS (2017)

"Recently, MnNiGe and MnCoGe intermetallic compounds have received a considerable attention due to the coupled tunable martensitic and magnetic transitions as well as giant magnetocaloric effect (MCE) they exhibit. In this work, by doping with Cr and varying of the annealing regime, a merged magnetostructural transition between a ferromagnetic orthorhombic and a paramagnetic hexagonal structure was received near room temperature in Mn1−xCrxCoGe melt-spun ribbons with x = 0.04 and 0.11. Structural and magnetic characterizations have been performed by X-ray diffraction, differential scanning calorimetry and magnetization measurements. It is found that, in ribbons with x = 0.04 (0.11) annealed at 1148 K, the peak value of the magnetic entropy change and the refrigerant capacity through the orthorhombic to hexagonal transition strongly increase with the annealing time from 7.3 (9.4) Jkg−1 K−1 to 10.6 (13.7) Jkg−1 K−1 and from 182 (235) Jkg−1 to 214 (267) Jkg−1, respectively, at 5 T for the time increase from 4 h to 8 h. Compared to bulk alloys of similar composition, the fabricated melt-spun ribbons show much broader working temperature range and a higher cooling efficiency."

Article

MnCrCoGe melt-spun ribbons Martensitic transformation Magnetostructural transition Magnetocaloric effect CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA FÍSICA

Analysis of voltage effect on holographic gratings by modulation transfer function

ROSANGELA COROMOTO FONTANILLA URDANETA ARTURO OLIVARES PEREZ Israel Fuentes Tapia Mónica Areli Ríos Velasco (2011)

The experimental data allow us to determine the imaging quality of holographic gratings with photosensitive film using organic material based on a polyvinyl alcohol matrix doped with potassium dichromate and nickel (II) chloride hexahydrate. The diffraction efficiency is estimated by different spatial frequencies, and the readout image quality is analyzed by the modulation transfer function. The experiment is carried out, with and without voltage application, at different spatial frequencies to obtain the image quality of photosensitive film. © 2011 Optical Society of America

Article

Voltage effect Holographic gratings CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA ÓPTICA ÓPTICA

Ablation and optical third-order nonlinearities in Ag nanoparticles

Carlos Torres Torres NESTOR PEREA LOPEZ JORGE ALEJANDRO REYES ESQUEDA Luis Rodríguez Fernández ALEJANDRO CRESPO SOSA JUAN CARLOS CHEANG WONG Alicia Oliver (2010)

"The optical damage associated with high intensity laser excitation of silver nanoparticles (NPs) was studied. In order to investigate the mechanisms of optical nonlinearity of a nanocomposite and their relation with its ablation threshold, a high-purity silica sample implanted with Ag ions was exposed to different nanosecond and picosecond laser irradiations. The magnitude and sign of picosecond refractive and absorptive nonlinearities were measured near and far from the surface plasmon resonance (SPR) of the Ag NPs with a self-diffraction technique. Saturable optical absorption and electronic polarization related to self-focusing were identified. Linear absorption is the main process involved in nanosecond laser ablation, but nonlinearities are important for ultrashort picosecond pulses when the absorptive process become significantly dependent on the irradiance. We estimated that near the resonance, picosecond intraband transitions allow an expanded distribution of energy among the NPs, in comparison to the energy distribution resulting in a case of far from resonance, when the most important absorption takes place in silica. We measured important differences in the ablation threshold and we estimated that the high selectiveness of the SPR of Ag NPs as well as their corresponding optical nonlinearities can be strongly significant for laser-induced controlled explosions, with potential applications for biomedical photothermal processes."

Article

Nonlinear optics Laser irradiation Metallic nanoparticles Kerr effect Nonlinear optical Absorption INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS CIENCIAS TECNOLÓGICAS