“Las aspiraciones laborales y el burnout en docentes universitarios de la Facultad de Ciencias Físicas y Matemáticas de una Universidad Nacional de Lima Metropolitana, 2017”

El presente estudio tuvo como objetivo establecer la relación que existe entre las Aspiraciones Laborales y el Burnout en docentes universitarios de la Facultad de Ciencias Físicas y Matemáticas de una Universidad de Lima Metropolitana, 201 7. La investigación fue realizada bajo un enfoque cuantitativo, de tipo descriptivo correlacional, cuyo diseño es transversal. La muestra estuvo conformada por 149 docentes universitarios entre hombres y mujeres. Los instrumentos utilizados fueron el cuestionario de Aspiraciones Laborales y el Inventario de Burnout de Maslach – MBI. Los resultados encontrados nos indican que no se encontró una relación estadísticamente significativa entre las Aspiraciones Laborales y el Burnout en docentes universitarios de la Facultad de Ciencias Físicas y Matemáticas de una Universidad de Lima Metropolitana, 201

Critical water activity and critical water content of freeze-dried strawberry powder as affected by maltodextrin and arabic gum

The adsorption isotherms (20 °C) and the relationship between water content and glass transition temperature were modeled in freeze-dried strawberry powder studying the effect of the addition of maltodextrin and arabic gum. Both compositional and physicochemical analyses of strawberry pulp were performed. If the midpoint of the glass transition is considered, the critical water activity that ensures the glassy state of the product during storage at 20 °C increased from 0.094 to 0.237-0.341 when maltodextrin and arabic gum were added, respectively. The increase in the critical water content was not so marked and it was noticeable only in arabic gum added sample (from 7.5 to 8.9. g water/100. g product), being this sample more stable. © 2011 Elsevier Ltd.Mosquera, LH.; Moraga Ballesteros, G.; Martínez Navarrete, N. (2012). Critical water activity and critical water content of freeze-dried strawberry powder as affected by maltodextrin and arabic gum. Food Research International. 47(2):201-2016. doi:10.1016/j.foodres.2011.05.019S201201647

Characterization study of a thermal oil-based carbon black solar nanofluid

Carbon nanoparticles are very useful in solar thermal applications, since they absorb much of the solar spectrum, are cheap and have excellent optical properties. Carbon nanoparticlesthermal oil-based nanofluid was prepared using two-step method with diphenyl sulfone as surfactant to achieve that nanoparticles remain suspended even at high temperatures. The size particle distribution was studied using two Dynamic Light Scattering systems at room and high temperature and also evaluated before and after exposing the nanofluid to a thermal treatment so that conditions closer to those in real applications were replicated. Moreover, the morphological changes due to the thermal treatment were observed with Transmission Electron Microscopy. Finally, the optical properties as the ballistic transmittance, absorption coefficient and scattering albedo of the base fluid as well as of the nanofluid were measured using a spectrophotometer with and without integrating sphere. The results of this study contribute to the knowledge about these solar nanofluids that are promising alternatives to the conventional solar collectors

Aplicación de la terapia de afrontamiento del estrés en dos poblaciones con alto estrés: pacientes crónicos y personas sanas

El objetivo de este estudio ha sido valorar la eficacia de la terapia cognitivo-conductual en el manejo del estrés para comprobar si disminuye la percepción de los síntomas somáticos autoinformados, tanto en personas sanas como en personas con lupus.This study has a double objective: on the one hand, to corroborate, once again, the efficacy of cognitive-behavioural stress management therapy in the control of certain psychological processes and, on the other hand, to take one more step by testing whether there is a reduction in the perception of self-reported somatic symptoms both in healthy people and in those with a chronic disease.Este estudio ha sido financiado por el Ministerio de Educación y Ciencia, Proyecto I+D SEJ2007-61857/PSIC

On the relationship between the specific heat enhancement of salt-based nanofluids and the ionic exchange capacity of nanoparticles

Nanoparticles have been used in thermal applications to increase the specific heat of the molten salts used in Concentrated Solar Power plants for thermal energy storage. Although several mechanisms for abnormal enhancement have been proposed, they are still being investigated and more research is necessary. However, this nanoparticle-salt interaction can also be found in chemical applications in which nanoparticles have proved suitable to be used as an adsorbent for nitrate removal given their high specific surface, reactivity and ionic exchange capacity. In this work, the ionic exchange capacity mechanism for the nanoparticles functionalization phenomenon was evaluated. The ionic exchange capacity of silica and alumina nanoparticles dispersed in lithium, sodium and potassium nitrates was measured. Fourier-transform infrared spectroscopy tests confirmed the adsorption of nitrate ions on the nanoparticle surface. A relationship between the ionic exchange capacity of nanoparticles and the specific heat enhancement of doped molten salts was proposed for the first time

Effect of storage temperature on the crispness, colour and bioactive compounds of an orange snack obtained by freeze-drying

[EN] Purpose A healthy and easy-to-use orange snack obtained from the freeze-dried orange pulp puree is proposed. Once the commercial packaging of the snack has been opened, the effect of conventional home storage temperature on its physicochemical properties and on the content of bioactive compounds has been studied. This research aims to recommend the consumer, and therefore the manufacturer, the best conditions for home storage of this product, keeping its nutritional quality and antioxidant capacity, as well as maintaining its colour and crispness. Design/methodology/approach The water content, water activity, hygroscopicity, crispness, colour, vitamin C, beta-carotene, total phenolic compounds and antioxidant activity were characterised both when the orange snack was newly obtained and after one, two and six months of storage inside zipper bags, at 4 and 20 oC. Findings The results indicated that, in these conditions, the orange snack increased its water content, causing a loss in both its porosity and its characteristic crispness. Nevertheless, the bioactive compounds remained stable throughout the storage period, with the exception of beta-carotene, the content of which decreased markedly when the orange snack was stored at 20 oC. Originality/value Few studies have evaluated the stability of food products during home storage. The findings showed that the maximum storage time to ensure a proper texture of the orange snack studied is between two and six months, both at 4 and 20 oC. However, from the point of view of the conservation of both vitamin C and, especially, of beta-carotene, it is recommended that this product be stored in refrigeration.The authors thank the Ministerio de Economia, Industria y Competitividad of Spain for the financial support given through the Project AGL 2017-89251-R (AEI/FEDER-UE) and the Ministerio de Universidades for the FPU grant (FPU14 / 02633) awarded to Ms. Andrea Silva.Silva Espinoza, MA.; Camacho Vidal, MM.; Martínez-Navarrete, N. (2021). Effect of storage temperature on the crispness, colour and bioactive compounds of an orange snack obtained by freeze-drying. British Food Journal. 123(6):2095-2106. https://doi.org/10.1108/BFJ-11-2020-1061S20952106123

Influence of the production method on the thermophysical properties of high temperature molten salt-based nanofluids

The potential use of molten salt-based nanofluids as thermal energy storage material in Concentrated Solar Power plants has gained attention over the last years due to their enhanced storage capacity. The possible effects of the salt-based nanofluid production at industrial scale have not been yet investigated, as this could influence the nanoparticles agglomeration and therefore their thermal and flow properties. Four methods were evaluated for the production of solar salt-based nanofluids containing 1 wt% of silica nanoparticles. The particle size distribution, the stability, the rheological behaviour and the specific heat of the samples were measured. Nanofluids prepared by means of a dry mixing method presented the lowest viscosity, trimodal particle size distribution and lack of stability. The commonly used dissolution method coupled with oven drying in a petri dish as well as the ball milling method presented non-Newtonian behaviour and intermediate values of particle size and stability. The new spray drying method proposed provided a monomodal particle size distribution with high stability but the highest viscosity and shear thickening behaviour. Results suggest that the four methods evaluated are appropriate for specific heat enhancement (up to 21.1%) but a commitment between stability and viscosity has to be achieved

Scales for social support for eating habits and exercise: psychometric properties

Fundamentos: El apoyo social puede introducir cambios favorables en el estilo de vida de cara a reducir el riesgo cardiovascular. El objetivo de este estudio fue verificar dichos cambios en la población clínica que participó en el mismo y presentar las propiedades psicométricas de dos escalas de apoyo social: los hábitos alimentarios y el ejercicio. Ambas fueron aplicadas en pacientes con síndrome metabólico (SM). Métodos: Participaron 135 sujetos en un programa de modificación de estilo de vida. Las medidas sociodemográficas, psicológicas y de estilo de vida fueron tomadas en el Hospital Universitario Virgen de las Nieves (HUVN) de Granada (España) durante 2013 y 2014. Se realizaron los siguientes análisis: análisis factorial confirmatorio (AFC), de la consistencia interna, de la sensibilidad al cambio y de la estabilidad temporal. Resultados: El AFC confirmó la estructura original de ambas escalas, excepto por la exclusión del factor 2 (familia) de la escala de apoyo social para el ejercicio. Para la escala de apoyo social, el ajuste local, todos los ítems presentaron altos valores de cargas factoriales y fiabilidades individuales (λ≥0,64 y R2≥0,41, respectivamente). Para la escala de ejercicio, el ajuste local, los ítems presentaron altos valores de cargas factoriales y fiabilidades individuales (λ≥0,62 y R2≥0,38, respectivamente). Los valores de consistencia interna resultaron entre adecuados y excelentes, con cifras de alfa de Cronbach entre 0,714 y 0,864. En cuanto a la sensibilidad al cambio, el grupo experimental aumentó la percepción del apoyo social para la alimentación y para el ejercicio. El grupo de control no presentó diferencias significativas. Conclusiones: Los resultados muestran niveles adecuados de validez y fiabilidad, demostrando que las escalas son adecuadas para evaluar el apoyo social en pacientes con SM.Background: Social support can introduce favorable changes in lifestyle to reduce the cardiovascular risk. The aim of this study was to verify these changes in the clinical population participating in this study and present the psychometric properties of the scales of social support for ‘Eating Habits’ and ‘Exercise’ in patients diagnosed with metabolic syndrome. Methods: 135 participants attending a programme for changing lifestyle habits. Sociodemographic, psychological, and lifestyle variables were assessed at the Hospital Universitario Virgen de las Nieves (HUVN) in Granada (Spain) between 2013 and 2014. The following procedures were used: Confirmatory factor analysis (CFA), internal consistency, sensibility to change and temporal stability. Results: The AFC confirmed the original structure of both scales, except for the exclusion of factor 2 (family) from the social support scale for the year. For the social support scale, the local adjustment, all items presented high values of factor loads and individual reliability (λ≥0.64 and R2≥0.41, respectively). For the exercise scale, the local adjustment, the items presented high values of factor loads and individual reliability (λ≥0.62 and R2≥0.38, respectively). Internal consistency values were between adequate and excellent, with Cronbach’s alpha figures between 0.714 and 0.864. Regarding sensitivity to change, the experimental group increased the perception of social support for food and exercise. The control group did not show significant differences. Conclusions: Our results show adequate indices for validity and reliability of the measures. Both measures appeared to be useful to assess social support in patients diagnosed with metabolic syndrome

Use of different biopolymers as carriers for purposes of obtaining a freeze-dried orange snack

[EN] In addition to colour, one of the most important qualifies of a snack-type product is its crunchy texture. A freeze-dried fruit snack is characterised by its low water content, which creates the problem of a loss of crunchiness related to its low glass transition temperature (Tg). In this sense, a common technique with which to increase the Tg of these types of products is to add different biopolymers. However, these compounds can, at the same time, affect the colour and texture of the product. In this study, different biopolymers have been tested in order to discover their similarities or differences in terms of hygroscopicity, antiplasticising character, colour and impact on the mechanical properties of a freeze-dried orange snack formulated from their different mixtures. Gum Arabic, maltodextrin, starch modified with octenylsuccinic anhydride, pea fibre, bamboo fibre and native corn starch have been selected as biopolymers. The impact of any of them on the studied properties can be confirmed, without any of them being more or less effective than the others.The authors thank the Ministerio de Economia y Competitividad for the financial support given through the Project AGL 2017-89251-R (AEI/FEDER-UE) and the Ministerio de Educacion for the FPU grant (FPU14/02633) awarded to Ms. Andrea Silva.Silva Espinoza, MA.; Camacho Vidal, MM.; Martínez-Navarrete, N. (2020). Use of different biopolymers as carriers for purposes of obtaining a freeze-dried orange snack. LWT - Food Science and Technology. 127:1-7. https://doi.org/10.1016/j.lwt.2020.109415S17127Acevedo, N. C., Schebor, C., & Buera, P. (2008). Non-enzymatic browning kinetics analysed through water–solids interactions and water mobility in dehydrated potato. Food Chemistry, 108(3), 900-906. doi:10.1016/j.foodchem.2007.11.057Agudelo, C., Igual, M., Camacho, M., & Martínez-Navarrete, N. (2016). Effect of process technology on the nutritional, functional, and physical quality of grapefruit powder. Food Science and Technology International, 23(1), 61-74. doi:10.1177/1082013216658368Bhusari, S. N., Muzaffar, K., & Kumar, P. (2014). Effect of carrier agents on physical and microstructural properties of spray dried tamarind pulp powder. Powder Technology, 266, 354-364. doi:10.1016/j.powtec.2014.06.038Brunauer, S., Deming, L. S., Deming, W. E., & Teller, E. (1940). On a Theory of the van der Waals Adsorption of Gases. Journal of the American Chemical Society, 62(7), 1723-1732. doi:10.1021/ja01864a025Brunauer, S., Emmett, P. H., & Teller, E. (1938). Adsorption of Gases in Multimolecular Layers. Journal of the American Chemical Society, 60(2), 309-319. doi:10.1021/ja01269a023Cano-Chauca, M., Stringheta, P. C., Ramos, A. M., & Cal-Vidal, J. (2005). Effect of the carriers on the microstructure of mango powder obtained by spray drying and its functional characterization. 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Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry, 81A(1), 89. doi:10.6028/jres.081a.011Martínez-Navarrete, N., Salvador, A., Oliva, C., & Camacho, M. M. (2019). Influence of biopolymers and freeze-drying shelf temperature on the quality of a mandarin snack. LWT, 99, 57-61. doi:10.1016/j.lwt.2018.09.040Moraga, G., Martı́nez-Navarrete, N., & Chiralt, A. (2004). Water sorption isotherms and glass transition in strawberries: influence of pretreatment. Journal of Food Engineering, 62(4), 315-321. doi:10.1016/s0260-8774(03)00245-0Moraga, G., Talens, P., Moraga, M. J., & Martínez-Navarrete, N. (2011). Implication of water activity and glass transition on the mechanical and optical properties of freeze-dried apple and banana slices. Journal of Food Engineering, 106(3), 212-219. doi:10.1016/j.jfoodeng.2011.05.009Pittia, P., & Sacchetti, G. (2008). Antiplasticization effect of water in amorphous foods. A review. 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Quality of a powdered grapefruit product formulated with biopolymers obtained by freeze-drying and spray-drying

[EN] Freeze-drying and spray-drying are two techniques used to produce dehydrated food products. Both techniques are easy to use and offer high sensory, nutritive value, and functional quality to foods. However, both processes become difficult for foods with high sugar and acid content, such as fruits. This is because these products, once dehydrated, moisten quickly, causing a change in their physical properties, mainly in the mechanical aspects related to the start of a caking phenomenon. Therefore, incorporating high molecular weight biopolymers that act as facilitators or processors, prevent the structural collapse of the product. The aim of this study was to select the best process, between freeze-drying or spray-drying, to obtain a powdered grapefruit product with the higher quality. The impact of the biopolymers used to stabilize the powdered product was also tested. The properties analyzed were the solubility, wettability, hygroscopicity, porosity, and color of the powder together with the flow behavior, both in air and water. The results of this study show that using the freeze-drying technique, products have a better flow behavior, greater porosity, and a color more like fresh grapefruit. Biopolymers, especially when in combination, have a positive effect on the quality parameters studied. Practical Application The results of this study allow freeze-drying to be proposed as a process to obtain a grapefruit product with better properties, both powdered and rehydrated, than that obtained by spray-drying. On the other hand, although the incorporation of biopolymers is necessary to facilitate the process and stabilize the product, no significant differences have been found between the different formulations tested, although it seems that their combination favours some of the properties of the powder, such as solubility, hygroscopicity, wetting time and dispersibility.The authors thank the Ministerio de Economia y Competitividad and the Ministerio de Economia, Industria y Competitividad for the financial support given through the Projects AGL 2012-39103 and AGL 2017-89251-R (AEI/FEDER-UE), respectively. Luis A. Egas-Astudillo thanks the Secretary of Higher Education, Science, Technology and Innovation (SENECYT) of the Republic of Ecuador for the contribution to this research.Egas-Astudillo, LA.; Martínez Navarrete, N.; Camacho Vidal, MM. (2021). Quality of a powdered grapefruit product formulated with biopolymers obtained by freeze-drying and spray-drying. Journal of Food Science. 86(6):2255-2263. https://doi.org/10.1111/1750-3841.157502255226386