Resumen En esta investigación se planteó como objetivo caracterizar color, textura y calidad sanitaria de pan adicionado con maíz criollo y cúrcuma. Se realizaron 14 diferentes panes empleando seis tipos de maíces (M1, M2, M3, M4, M5 y M6). Los principales hallazgos fueron a) El color de los maíces, harinas nixtamalizada y masas tuvieron diferencia significativa (p < 0.05) al comparar valores medios de parámetros de Luminosidad, a* y b*. Los maíces azules y rojizo M2 (37.01), M3 (44.06) y M6 (41.07) y, amarillos y amarillo-naranja M1 (21.26), M4 (15.92) y M5 (26.01) presentaron los valores inferiores en L* y superiores en b*, respectivamente. La menor diferencia en color ∆E encontrada en el proceso de transformación de maíz a harina y masa, fue para maíces amarillos. b) En el pan de maíz se encontraron diferencias significativas en variable a* al compararse el mismo tipo de pan durante tres días consecutivos, en los panes BM1, BM5 y BM6, con una disminución de 7.5, 2.6 y 16.9%, con respecto al primer día. c) La calidad sanitaria del pan de trigo mejora con la adición de maíz nixtamalizado y cúrcuma. En los panes adicionados de maíz los que presentaron menor cantidad de colonias de hongos fueron los maíces azules y rojo (M2, M3 y M6). d) La dureza del pan de maíz criollo y cúrcuma no presentó diferencias durante tres días consecutivos beneficiando su conservación. El pan de maíz amarillo y cúrcuma BM1-C mostró incrementos en la dureza en los días 2 y 3.

Abstract The objective of this research was to characterize the color, texture and sanitary quality of bread added with creole corn and turmeric. Fourteen different breads were made using six types of corn (M1, M2, M3, M4, M5 and M6). The main findings were a) The color of the corn, nixtamalized flours and doughs had a significant difference (p < 0.05) when comparing mean values of Luminosity, a* and b* parameters. Blue and reddish corn M2 (37.01), M3 (44.06) and M6 (41.07) and, yellow and yellow orange M1 (21.26), M4 (15.92) and M5 (26.01) presented the lowest values in L* and highest in b*, respectively. The smallest difference in color ∆E found in the transformation process from corn to flour and dough, was for yellow corn. b) In corn bread, significant differences in variable a* were found when comparing the same type of bread for three consecutive days, in breads BM1, BM5 and BM6, with a decrease of 7.5, 2.6 and 16.9%, with respect to the first day. c) The sanitary quality of wheat bread improves with the addition of nixtamalized corn and turmeric. The blue and red corn (M2, M3 and M6) showed the lowest number of fungal colonies in the breads with corn additives. d) The hardness of the bread made with creole corn and turmeric did not show differences during three consecutive days, benefiting its conservation. The yellow corn and turmeric bread BM1-C showed increases in the hardness on days 2 and 3, and the yellow corn and turmeric bread BM1-C showed increases in the hardness on days 2 and 3.

X-ray Photoelectron Spectroscopy (XPS) and Photoacoustic (PA) techniques are useful to identify the structure and optical properties of chemical compounds used in archaeology, among others. In the present study XPS and PA techniques were used to analyze seven samples obtained from the Talavera House, during the conservation and restoration works carried out in the 2012-2013 period. Talavera House is located between the República del Salvador, Talavera and Roldán streets, in the historic center of Mexico City. The objective of this study was to identify the chemical compounds added to the lime when burned in the furnace and its use in the tanneries during the 18th century, both elements located in the second yard, as well as in the construction of the corridor in the 20th century located in the first courtyard. The samples were collected at these points and analyzed by XPS and Photoacoustic (PA) techniques, comparing these results with other excavated sites.

Abstract The cosmetic industry has turned its attention to using vegetable products; the number of different vegetable oils used in the cosmetic industry has risen in the last years. Therefore, there are opportunities for development and innovation for the cosmetic sector keeping in mind the growing concern for personal well-being. Being necessary to develop new, and more accurate measurement methods not only to assure the product quality, also to understand the effect of the molecular interactions in order to develop new products. In this work, the so-called photopyroelectric techniques are used for studying the thermal effusivity and diffusivity of wheat germ, mamey seed, walnut, coconut, and linseed oils. The thermal conductivity was calculated using a mathematical relationship, and density was measured. Therefore, full thermal characterization is achieved. The obtained values for the studied oils are closed to other vegetable oils already reported. This similarity is partially a consequence of the similar chemical structure presented in this type of materials.

Abstract In this study the thermal conductivity of a commercial ceramic is determined considering that this property is an essential factor on the building materials. This is the primary indicator of the material suitableness for energy transfer, considering that this kind of construction supplies has many applications as thermal insulations. In this sense, we consider that a commercial tile is usually composed of three layers: substrate, a so-called engine layer, and an enamel layer. Likewise, the thermal properties of the different layers were obtained individually by using two photothermal techniques on the ceramic material; the ceramic tile density was obtained using the Archimedes method. The calculated values show a wide range of thermal conductivity values for the different layers, ranging from1.3 to 4 W m - 1K - 1.

Abstract: The main purpose of the present study was to characterize the juice and rind of the Persian lime (Citrus latifolia) with different quality of samples, by means of the Photoacoustic Spectroscopy (PAS) technique. In agreement to the Mexican quality standards, the samples under study were classified into four degrees of quality; i.e. Extra, Second, Third and Waste classes. We have used PAS to characterize the optical properties of each one of the samples. Thus, we have obtained the absorption spectra of the juice as well as in that part of the rind called flavedo. After that, using another different photoacoustic configuration, we have measured the water vapor permeability of the albedo; i.e. the innermost, white and spongy layer of the rind. Our results show that PAS is a reliable technique to get the grading quality of samples in situ of fresh fruits such as Persian limes by means of the study of some of their physical properties.

Abstract Over the last years extensively research has been carried out on full or partial substitution of supplies resources coming from renewable resources on traditionally non-renewable, in the case of the automobile sector there are progresses in bio-combustibles (biofuel) and synthetic oils coming from vegetable sources. There are strong efforts to find oil additives which can improve oils features in automobile industry, by adding vegetables oils to commercial lubricant oils, is expected to improve oil thermal stability. In the present research, different ratios of castor oil (ricinus comunis)-motor oil blends were obtained and their thermal properties were characterized by using the so-called Back and Front Photopyroelectric (BPPE/FPPE) techniques. Several oil-additives concentrations were measured and thermal diffusivities and effusivities as well as densities are reported, getting full thermal characterization for every concentration.

Abstract Glucose is an important molecule, it is responsible for providing energy to cells in our body, in human glucose appears in blood, excessive glucose levels in the blood are an indicator of diabetes mellitus, therefore it is important to measure it. To test the feasibility of photothermal techniques to measure glucose, thermal properties of glucose in aqueous solution were determined in the 0.7 to 3.2 mg/ml range. Thermal effusivity diminishes as glucose concentration increase. Obtained results show that used setups can measure glucose concentrations up to 600 μg/ml. Full thermal characterization for water-glucose mixtures is presented in this work.

Abstract: Photoacoustic Spectroscopy (PAS) stand outs among Photothermal techniques due to its versatility for the characterization of different types of materials, including biological samples. In this study, were compared and analyzed by PAS, the differences between the optical absorption spectra of blood of male Fisher rats, in three cases, control (healthy rats), liver damage and liver damage treated with Curcuma longa. The experimental results show differences in the optical absorption spectra of each analysed case, therefore PAS would be proposed as a non conventional complementary technique, to study the effect of Curcuma longa in induced liver damage for an animal model.

Resumen: La Espectroscopia Fotoacústica (EFA), ha destacado de entre las técnicas fototérmicas por su versatilidad para la caracterización de diversos tipos de muestras, incluyendo las de tipo biológicas. En este estudio, se compararon y analizaron mediante EFA, las diferencias entre los espectros de absorción ópticos de sangre de ratas macho Fisher en tres casos, control (ratas sanas), con daño hepático, y con daño hepático tratadas con Curcuma longa. Los resultados experimentales demostraron diferencias en los espectros de absorción ópticos de cada caso analizado, por lo que EFA se propondría como una técnica complementaria, no convencional para el estudio del efecto de la Curcuma longa en daño hepático inducido en modelo animal.

Abstract: The failure in the neuron regeneration in the central nervous system (CNS) in higher vertebrates, is a not completely solved problem, this limits the rehabilitation of many motor conducts after an injury in the spinal cord. In neuronal regeneration multiple factors are involved, between them those that induce the neurite outgrowth which has been studied to try to encourage the extension and reconnection of the injury neurons with their blanks. The regeneration of the CNS of leeches has been intensely studied because allows to approach the problem at different levels with different techniques. In this study the optical absorption spectrum of the CNS and the tissue of the leech H. officinalis was obtained, by using photoacoustic spectroscopy (PAS), in order to investigate the optimal wavelenghts for later irradiation of CNS cells and tissue of H. officinalis. The results of this study show that the CNS of these organisms absorbs in the region of 300 nm to 500 nm, and the tissue samples has a maximun of optical absorption near to 300 nm, besides were observed evident differences between the optical absorption spectra of CNS with injury and the control (without injury).

Resumen: La falla en la regeneración de las neuronas del sistema nervioso central (SNC) en vertebrados superiores es un problema que no se ha resuelto completamente, esto limita la rehabilitación de muchas conductas motoras después de una lesión en la médula espinal. En la regeneración neuronal intervienen múltiples factores y de estos, los que inducen el crecimiento neurítico se han estudiado para intentar favorecer la extensión y la reconexión de las neuronas lesionadas con sus blancos. La regeneración del SNC de sanguijuelas se ha estudiado intensamente porque permite abordar el problema a diferentes niveles con distintas técnicas, en este trabajo se obtuvo el espectro de absorción óptico, con espectroscopía fotoacústica (EFA), del SNC y de tejido de la sanguijuela Haementeria officinalis, con el objetivo de conocer las longitudes de onda óptimas para la irradiación posterior de células del SNC y de tejido H. officinalis. Los resultados de este estudio muestran que el SNC de estos organismos absorbe en la region comprendida de 300 nm a 500 nm, y las muestras de tejido tienen un máximo de absorción óptico proximo a 300 nm, además se observaron diferencias evidentes entre los espectros de absorción ópticos del SNC con lesión y el control (sin lesión).

Thermal parameters of biodiesel containing Au nanoparticles was characterized by thermal lens technique (TL) and inverse photopyroelectric (IPPE) technique. In the case of the TL spectrometry technique, two lasers in the mismatched mode experimental configuration were used in order to obtain the thermal diffusivity (D) of the biodiesel. On the other hand, the sample thermal effusivity (e) was obtained by using the IPPE technique where the temperature variation of the sample, exposed to modulated radiation, is measured with a pyroelectric sensor. In this technique a He-Ne laser was used as the excitation source and was operated at 632 nm with an output power of 120 mW. From the obtained thermal-diffusivity (D) and thermal effusivity (e) values, the thermal conductivity (k) was calculated from the relationship e = k/ √D. The obtained thermal parameters were compared with the values of the thermal parameters of literature. Measurements of particle size and absorption were determined by complementary techniques such as transmission electron microscopy (TEM) and photoacoustic (PA) spectroscopy, respectively. Our work has applications as high functioning heat transfer fluids in automotive electronic cooling systems and in micro-channel heat sinks (Wen et al., 2006).

Los parámetros térmicos del biodiesel conteniendo nanopartículas de Au fueron caracterizados por las técnicas de lente térmica (TL) y técnica fotopiroeléctrica inversa (IPPE). En el caso de TL, en la configuración experimental en el modo desacoplado de dos láseres fue usado con la finalidad de obtener la difusividad térmica (D) del biodiesel. Por otra parte, la efusividad térmica de la muestra (e) fue obtenida mediante el uso de la técnica IPPE donde la variación de la temperatura de la muestra, expuesta a la luz modulada, es medida con un sensor piroeléctrico. En esta técnica un láser de He-Ne fue usado como fuente de excitación y fue operado a 632 nm con una potencia de salida de 120 mW. De los valores de la difusividad térmica (D) y la efusividad térmica (e), la conductividad térmica (k) fue calculada de la relación e = k/ √D. Los parámetros térmicos obtenidos fueron comparados con los valores de los parámetros térmicos de la literatura. La mediciones del tamaño de partícula y de la absorción fueron determinados por técnicas complementarias tales como TEM y espectroscopia fotoacústica (PA), respectivamente. Nuestro trabajo tiene aplicaciones en fluidos de alto rendimiento y en microcanales como disipadores de calor (Wen et al., 2006).

Zinc-blende GaAs layers were prepared on (100) Si and glass substrates by r.f. magnetron sputtering. The morphology of GaAs layers is analyzed by means of atomic force microscopy (AFM) and scanning electron microscopy (FE-SEM), to determine the sample topography and growth type. The compositional analysis was performed by means of energy dispersive X-ray spectroscopy (EDS), in order to obtain information of the atomic percentages of the elements and their spatial distribution in the samples. The optical properties of the layers are discussed from the results of UV-Vis absorption, and Photoacoustic spectroscopy (PAS). Finally, the Raman shift of the GaAs phonon modes are studied as function of the penetration depth of laser wavelength used to excite the sample on Raman microscopy.

Photothermal techniques have been used to characterize the thermal and optical parameters of different homogeneous materials. Among these techniques the photopyroelectric and photoacoustic microscopy have been applied for obtaining superficial and in-depth thermal images of several materials with the possibility to obtain sub-superficial characteristics by changing the modulation frequency of the incident light on the sample under study. In the present research the thermal image of a non-homogeneous material such as a biological object, in this case a maize seed was obtained by photopyroelectric microscopy. The differences in the seed structural components were observed through its thermal image obtained from the photopyroelectric signal when the modulated light is scanned on the pyroelectric sensor, which is in good thermal contact with the sample. A scale of colors is used to represent the different values of the photopyroelectric signal, as a function of the scan coordinates, which allows observing better the seed components. The differences of photopyroelectric signal are caused by the inhomogeneities in the optical and thermal properties of the material which locally constituting the sample. In the case of this study the sample was an infected seed with "Palomilla" (Ostrinia nubilalis) plague and the thermal image shows the damage at the interior of the maize seed due to this plague.

Diversos materiales homogéneos han sido estudiados mediante técnicas fototérmicas, con la finalidad de caracterizarlos en los parámetros térmicos y ópticos. De estas técnicas la Microscopia Fotoacústica y Fotopiroeléctrica se han aplicado para la obtención de imágenes térmicas a nivel superficial y a profundidad de diversos materiales con la posibilidad de detallar al interior del material, dependiendo de la frecuencia de modulación de la luz que incide sobre la muestra. En el presente estudio se obtuvo la imagen térmica, mediante Microscopía Fotopiroeléctrica, de un objeto biológico que presenta una no-homogeneidad como lo es la semilla de maíz. Las diferencias en las estructuras componentes de la semilla pudo ser observada a través de su imagen térmica, en donde se puede hacer una interpretación de esta mediante una escala de colores que se obtiene de las diferencias de potencial de la señal fotopiroeléctrica al realizarse el barrido sobre el sensor piroeléctrico que está en contacto con la muestra. Estas diferencias de señal fotopiroeléctrica son causadas por variaciones del tipo de material que constituyen localmente la muestra y que presentan diferencias en sus parámetros térmicos. En el caso de este estudio la muestra fue una semilla infectada por plaga palomilla (Ostrinia nubilalis) y la imagen térmica muestra el daño producido en el interior de la semilla de maíz por esta plaga.

Development and use of food packaging based on biomaterials have gained significant interest due to the need to reduce and replace the use of plastics and synthetic packaging for eco-friendly materials. In addition, these materials can act as semipermeable barriers while preserving the organoleptic characteristics of plant products. In the present work, gelatin-carboxymethylcellulose based edible films were prepared studying the effects of glycerol content and pH on their physicochemical properties. Also, the effect of the films on the postharvest shelf-life of guava fruit was determined. The characterization of the films was performed through the puncture strength test, water vapor diffusion coefficient and water solubility. Results indicated that both, glycerol and pH were determinant on the evaluated properties. Fruits coated with edible films showed lower weight losses and lower firmness losses as compared to control fruits, however, no differences were found in °Brix.

El interés en el desarrollo y uso de empaques alimenticios a base de biomateriales ha venido creciendo debido en gran medida a la necesidad de reducir y sustituir el empleo de plásticos y envases sintéticos, por materiales menos agresivos con el medio ambiente. Además, estos materiales pueden actuar como barreras semipermeables preservando las características organolépticas de productos vegetales. En este sentido, en la presente investigación se elaboraron películas comestibles a base de gelatina y carboximetilcelulosa (CMC) estudiando el efecto del contenido de glicerol y pH en sus propiedades fisicoquímicas. Asimismo, se evaluó el efecto de las películas en la vida postcosecha de frutos de guayaba. La caracterización de las películas se realizó a través de la resistencia a la ruptura, coeficiente de difusión al vapor de agua y solubilidad en agua. Estas propiedades estuvieron en función del contenido de glicerol y el pH de la solución formadora de película. Los resultados indicaron que tanto la incorporación de glicerol como el pH influyeron de manera importante en las propiedades evaluadas. Los frutos recubiertos con películas de gelatina-CMC presentaron menores pérdidas de peso y menores pérdidas de firmeza en comparación con los frutos control, sin embargo, no se identificaron diferencias en °Brix.

R6G dye with gold nanoparticles was prepared in water solution. Using a thermal lens experimental setup, the thermal diffusivity of R6G in presence of gold nanoparticles with Au different concentration was measured. The results show that, the thermal diffusivity of R6G dye mixed with gold nanoparticles increases with the increase of particle metallic concentration, enhancing the thermal diffusivity in the solution. The thermal diffusivity of the samples was studied for a constant concentration of R6G dye 0.1 g/L. The diffusivities were obtained by using the thermal lens aberrant model with lasers arranged in the mismatched mode. The characteristic time constant of the transient thermal lens was obtained by fitting the theoretical expression, for transient thermal lens, to the experimental data. UV-Vis spectroscopy and TEM were used to characterize the R6G dye gold nanoparticles.

It was designed and performed an analogical electronic circuit to control a shutter driver (model UNIBLITZ VMM-D1). Parallel to this it was developed a Labview program for a computerized control of the same device. The analogical circuit provides a minimum opening time of 10 ms. On the other hand the program in Labview provides a minimum time for opening of 5 ms and also with the option to regulate the number and the frequency of the shutter pulses. This shutter is used to provide pulses with 40mW of power from an Ar+ laser beam, generating thermal gradients in liquid samples. In this work we reported the application of this shutter to generate thermal gradients in a solution containing gold nanoparticles in water with the purpose of obtaining its thermal diffusivity by means of the thermal lens technique. Finally we discussed the advantages and disadvantages between the performed shutter controls.

Se diseño y construyo un circuito electrónico analógico para controlar un dispositivo electrónico, para el disparo de un obturador (modelo UNIBLITZ VMM-D1). Paralelamente se desarrollo un programa en Labview para el control computarizado de este mismo dispositivo. El circuito analógico proporciona un tiempo de abertura mínimo de 10 ms. Por su parte el programa en Labview nos proporciona un tiempo de abertura de 5 ms y con la opción de regular el número y la frecuencia de los pulsos del obturador. Este obturador es utilizado para proporcionar pulsos de 40 mW de potencia de un haz láser de Ar+, generando gradientes térmicos en muestras líquidas. En este trabajo reportamos la aplicación de este obturador para generar los gradientes térmicos en una solución conteniendo nanopartículas de oro en agua con la finalidad de obtener su difusividad térmica mediante la técnica de lente térmica. Finalmente discutimos las ventajas y desventajas de los dos modos de control.