Development of analytical methods for the characterization of tempera paintings at micro- and nano-scale and their deterioration and biodeterioration processes

Egg (the whole, the yolk or the white) is a natural product used since ancient times as tempera painting medium mainly in Europe and the Mediterranean Basin countries. In addition, egg is a complex multicomponent microstructured system susceptible of being influenced by the pigments that compose the paints, as well as a source of nutrient susceptible of biodeterioration. Modifying effect of artists' pigments on the binding medium as well as, the microbial biodeterioration are responsible for changes in the structure and composition of the binding medium and, consequently, on the physico-chemical properties of the paint. For this purpose, analytical techniques such as Fourier transform infrared spectroscopy - attenuated total reflection (FTIR-ATR) was used for the chemical characterization, Field emission scanning microscopy (FESEM) and Atomic force microscopy - nanoindentation (AFM-nanoindentation) were run for morphological and mechanical characterization of the deterioration processes resulted from the pigment-binder interactions involved in tempera painting. On the other hand, the current research report the application of the voltammetry of microparticles (VMP), complemented with FTIR-ATR, FESEM and AFM-nanoindentation techniques to monitor the deterioration of a series of tempera reconstructed model paint specimens under the action of different biological agents. This methodology would be of application for identifying the type of biological agent causing deterioration of painting, which is an important problem affecting cultural heritage. The analysis of biodeterioration processes is complicated by the fact that the action of microorganisms can affect both pigment and binding media. The deterioration of pictorial specimens by Acremonium chrysogenum, Aspergillus niger, Mucor rouxii, Penicillium chrysogenum and Trichoderma pseudokoningii fungi and Arthrobacter oxydans, Bacillus amyloliquefaciens and Streptomyces cellulofans bacteria was tested using sample-modified graphite electrodes immersed into aqueous electrolytes. Finally, the study carried out by means of FTIR-ATR, FESEM and AFM-nanoindentation confirms that egg proteins attached to the pigment grains changes their secondary structures. The results obtained also confirm that proteins and phospholipids are prevalently established linkages with the solid particles of pigment whereas triglycerides should be integrated in the complex binding network responsible for the cohesion of the paint film. Interactions between egg components with solid pigment particles are described and correlated with micromorphology and mechanical properties determined at micro- and nano-scale on the reconstructed model paint specimens. As a result of the crossing of VMP data with the results obtained by means of FTIR, FESEM and AFM-nanoindentation, the voltammetric signals obtained were associated to the electrochemical reduction of pigments and different complexes associated to the binding media. These results were particularly relevant in the study of biodeterioration, to allowing the electrochemical monitoring of biological attack.El huevo (entero, yema o clara) es un producto natural utilizado desde la antigüedad como medio aglutinante en la pintura al temple, principalmente en Europa y los países de la cuenca mediterránea. Además, el huevo es un complejo sistema multicomponente microestructurado susceptible de ser alterado por los pigmentos que componen las pinturas, así como fuente de nutrientes susceptible de biodeterioro. El efecto de los pigmentos sobre el medio aglutinante, así como el biodeterioro microbiano son responsables de cambios en la estructura y composición del medio aglutinante y, por consiguiente, en las propiedades fisicoquímicas de la pintura. Es por esto que, se utilizaron técnicas analíticas como la Espectroscopía Infrarroja por Transformada de Fourier en modo Reflexión Total Atenuada (FTIR-ATR), para la caracterización química de los procesos de deterioro resultantes de las interacciones pigmento-aglutinante en la pintura al temple. Así mismo, se utilizó Microscopía Electrónica de Emisión de Barrido (FESEM) para el estudio morfológico de las muestras, y para el estudio de las propiedades mecánicas Microscopía de Fuerza Atómica en modo Nanoindentación (AFM-nanoindentación). Por otro lado, la presente investigación propone el uso de la Voltamperometría de Micropartículas (VMP), en conjunto con otras técnicas de análisis como FTIR-ATR, FESEM y AFM-nanoindentación para el estudio del biodeterioro producido por hongos y bacterias sobre una serie muestras pictóricas sometidas. El estudio de las alteraciones causadas por el biodeterioro es complicado por el hecho de que la acción de los microorganismos puede afectar tanto al pigmento como al medio aglutinante. Para esto, se prepararon una serie de muestras de pinturas al temple y emulsión que fueron inoculadas con los hongos Acremonium chrysogenum, Aspergillus niger, Mucor rouxii, Penicillium chrysogenum, y Trichoderma pseudokoningii, y las bacterias Arthrobacter oxydans, Bacillus amyloliquefaciens y Streptomyces cellulofans. El estudio voltamperometrico se realizó utilizando electrodos de grafito modificados con las muestras inmersos en un electrolito acuoso. Las conclusiones obtenidas de manera general, apuntan a que las proteínas presentes en el huevo cambian su estructura secundaria al adherirse a los granos de pigmento. La información química, morfológica y mecánica obtenida por las diferentes técnicas de análisis instrumental es consistente. Finalmente, como resultado del cruce de los datos VMP con los resultados obtenidos mediante FTIR, FESEM y AFM-nanoindentación, las señales voltamperometricas obtenidas se asociaron a la reducción electroquímica de los pigmentos y a los complejos formados con el medio aglutinante. Estos resultados fueron particularmente relevantes en el estudio del biodeterioro de las películas pictóricas inoculadas, para permitir la monitorización electroquímica del ataque microbiológico.L'ou (sencer, rovell o clara) és un producte natural utilitzat des de l'antiguitat com a mitjà aglutinant en la pintura al tremp, principalment a Europa i els països de la conca mediterrània. A més, l'ou és un complex sistema multicomponent MICROESTRUCTURAT susceptible de ser alterat pels pigments que componen les pintures, així com a font de nutrients susceptible de biodeterioració. L'efecte dels pigments sobre el medi aglutinant, així com el BIODETERIORI microbià són responsables de canvis en l'estructura i composició del medi aglutinant i, per tant, en les propietats fisicoquímiques de la pintura. És per això que, es van utilitzar tècniques analítiques com l'Espectroscòpia Infraroja per Transformada de Fourier en mode Reflexió Total Atenuada (FTIR-ATR), per a la caracterització química dels processos de deteriorament resultants de les interaccions pigment-aglutinant en la pintura al tremp. Així mateix, es va utilitzar Microscòpia Electrònica d'emissió de Rastreig (FESEM) per a l'estudi morfològic de les mostres, i per a l'estudi de les propietats mecàniques Microscòpia de Força Atòmica en mode Nanoindentació (AFM-nanoindentació). D'altra banda, la present investigació proposa l'ús de la Voltamperometría de Micropartícules (VMP), en conjunt amb altres tècniques d'anàlisi, com FTIR-ATR, FESEM i AFM-nanoindentació per a l'estudi de l'biodeterioració produït per fongs i bacteris sobre una sèrie de mostres pictòriques sotmeses. L'estudi de les alteracions causades pel biodeteriori és complicat pel fet que l'acció dels microorganismes pot afectar tant el pigment com al medi aglutinant. Per això, es van preparar una sèrie de mostres de pintures al tremp i emulsió que van ser inoculades amb els fongs Acremonium chrysogenum, Aspergillus niger, Mucor rouxii, Penicillium chrysogenum, i Trichoderma pseudokoningii i els bacteris Arthrobacter oxydans, Bacillus amyloliquefaciens i Streptomyces cellulofans. L'estudi voltamperomètric es va realitzar utilitzant electrodes de grafit modificats amb les mostres immersos en un electròlit aquós. Les conclusions obtingudes de manera general, apunten que les proteïnes presents en l'ou canvien la seva estructura secundària al adherir-se als grans de pigment. La informació química, morfològica i mecànica obtinguda per les diferents tècniques d'anàlisi instrumental és consistent. Finalment, com a resultat de l'encreuament de les dades VMP amb els resultats obtinguts mitjançant FTIR, FESEM i AFM-nanoindentació, els senyals voltamperomètrics obtinguts es van associar a la reducció electroquímica dels pigments i als complexos formats amb el medi aglutinant. Aquests resultats van ser particularment rellevants en l'estudi del biodeteriori de les pel·lícules pictòriques inoculades, per tal de permetre la monitorització electroquímica de l'atac microbiològic.Ortiz Miranda, A. (2017). Development of analytical methods for the characterization of tempera paintings at micro- and nano-scale and their deterioration and biodeterioration processes [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90571TESI

Haiti and the United States During the 1980s and 1990s: Refugees, Immigration, and Foreign Policy

This Article discusses various aspects of United States/Haitian relations during the 1980s and 1990s. It examines United States domestic immigration law and policy as applied to Haitian asylum-seekers who have reached the shores of the United States or who have been apprehended in the territorial sea. Additionally, this Article will examine foreign policy aimed at preventing Haitians from fleeing their homeland. It will discuss legislative policies of the United States Congress in light of the domestic and foreign policies pursued by the executive branch toward Haiti. Finally, it will conclude with certain observations and recommendations

Biological control of diamondback moth

The diamondback moth Plutella xylostella L. (Lepidoptera: Plutellidae) is a serious pest of economically important crucifer crops such as cabbage. The moth has developed resistance to all tested insecticides and further studies on the potential role of factors affecting P. xylostella survival, including natural enemies, are urgently needed. One aim of this thesis was to identify the species that are natural enemies of P. xylostella and to evaluate their role in the natural biological control of this pest insect. Another aim was to gain knowledge that could be used to develop biological pest control methods with the potential for high efficacy against P. xylostella, thus avoiding the side effects of traditional chemical control while maintaining production and profits. This study was carried out in Estelí, Nicaragua during five cropping seasons, from 2006 to 2008. The results indicate that there is a broad spectrum of predators present in habitats within and around cabbage fields, and that these have the capacity to feed on P. xylostella eggs and larvae under laboratory conditions. The predators with the highest consumption rates were insect larvae (Syrphidae) and spiders in the families Linyphiidae and Salticidae. The most abundant predators, which also had the highest consumption rate and consequently the highest potential for suppressing P. xylostella populations, were spiders (Lycosidae) and rove beetles (Staphylinidae), although sheet weaving spiders, jumping spiders, assassin bugs (Reduviidae) and damsel bugs (Nabidae) may also be important. It is concluded that these generalist predators should be considered for further study in the field as candidate species with a role in the management of the pest P. xylostella. An exclusion experiment in the field showed that flying and ground dwelling natural enemies of P. xylostella interact negatively with each other. In another study, leaf damage was found to be higher in insecticide treated fields than in untreated fields as a combined consequence of insecticide resistance in the pest and lower predation from natural enemies which are reduced in number by the insecticide applications. In the last study, the main focus was to identify whether a combination of bio-control agents, i.e. parasitoids and a biological insecticide (Bt), interact additively, negatively or positively, in affecting the mortality of P. xylostella. It is concluded that a combination of control measures, including the promotion of predators and parasitoids, is probably needed to achieve sustainable biological control of the diamondback moth. To succeed with such approaches we must, however, learn more about the particular roles of different predators

An Agenda for the Commission on Immigration Reform

This Article offers agenda topics for the members of the Commission on Immigration Reform (Commission) to consider in their deliberations in the early 1990s. The topics discussed in the Article cover those that Congress specifically requested the Commission to evaluate, as well as other topics that the Commission may have found within its authority to evaluate. Final recommendations made by the Commission to the Congress in its final report due in 1997 had the potential to shape legislative policy choices in the area of immigration reform during the first part of the twenty-first century

Rethinking the Role of Politics in United States Immigration Law: The Helsinki Accords and Ideological Exclusion of Aliens

In this Article, Mr. Miranda examines the statutory framework and case law addressing the ideological exclusion of aliens from the United States in light of the Helsinki Accords. The ideological exclusion, embodied in the Immigration and Nationality Act of 1952, is used to bar entry of noncitizens to the United States because of their espousal of proscribed ideologies. Congress temporarily suspended the ideological provisions until March 1, 1989 to allow for further comprehensive and permanent revisions in the area of deportation and exclusion. The Article is intended to contribute to the ongoing dialogue concerning such permanent and much needed changes

Geometrical constraints on dark energy models

This contribution intends to give a pedagogical introduction to the topic of dark energy (the mysterious agent supposed to drive the observed late time acceleration of the Universe) and to various observational tests which require only assumptions on the geometry of the Universe. Those tests are the supernovae luminosity, the CMB shift, the direct Hubble data, and the baryon acoustic oscillations test. An historical overview of Cosmology is followed by some generalities on FRW spacetimes (the best large-scale description of the Universe), and then the test themselves are discussed. A convenient section on statistical inference is included as well.Comment: 28 pages, 15 pages, lecture notes prepared for the ``Advanced Summer School in Physics 2007" organized by Cinvestav (Mexico DF

Governing fair trade coffee supply: dynamics and challenges in small farmers' organisations

[EN] Farmers' organizations are essential actors in fair trade certification schemes, and therefore in delivering their associated benefits for poor small-scale farmers. However, the dynamics and challenges faced by these cooperative organizations have been largely bypassed in the fair trade literature. In this context, this paper aims to unpack the multiple, coexisting and interwoven marketing channels available for small-scale coffee producers, unveiling potential sources of uncertainty and tensions among competing actors and interests, and identifying and assessing the strategies used by organizations to influence farmers' marketing decisions. The analysis comprises two case studies based in the department of Huehuetenango (Guatemala), where the existence of distinct marketing channels combines with processes of product differentiation, namely organic production. Results show the limitations of standard fair trade mechanisms to secure farmers' engagement with cooperative organizations. Rather, technical advice to improve farming practices and quality construction seem to be a more effective mechanism to govern this collective supply chain. Nevertheless, these strategies could be further constrained by productive and organizational factors, affecting the sustainability of potential benefits delivered by these key collective actors. Copyright (c) 2014 John Wiley & Sons, Ltd and ERP EnvironmentThis paper presents some results from the research project ‘Small-scale farmers in Fairtrade schemes in Latin America: collective action, governance and social capital’, funded by the Cooperation for Development Centre of the Universitat Politècnica de València. The authors thank Oxfam-INTERMON for the support provided to this research, particularly to Juanjo Martínez. We also thank members of the CRECER Association of Guatemala and staff (in particular Lucas Silvestre, Gregorio Alva and Javier Jacinto) and members of the organizations Guaya’b and CODECH for their indispensable willingness to participate in this research. The authors gratefully acknowledge comments and suggestions made by the editor and the two anonymous referees.Ortiz Miranda, D.; Moragues Faus, AM. (2015). Governing fair trade coffee supply: dynamics and challenges in small farmers' organisations. Sustainable Development. 23(1):41-54. doi:10.1002/SD.1570415423

Relación del Control Glucémico, Función Cognitiva y las Funciones Ejecutivas en el Adulto Mayor con Diabetes Tipo 2: Revisión Sistemática

Aim: To review the available evidence to show the relationship between glycemic control, cognitive function and executive functions in the AM with T2D.Methods: The literature search was conducted in English and Spanish, in 14 databases, Open Access, and the Google search engine. Based on the model proposed by Cooper (2007), for the synthesis of the literature. The studies were assessed for validity through CASPe guide for case-control studies.Results: We analyzed correlation 11estudies 100% of the studies showed glycemic control relationship to cognitive impairment and executive function in AM with DT2. Studies agree that the AM with DT2 have cognitive impairment, compared with AM without DT2, therefore there is a deficit in the AM to perform executive functions.Conclusions: Based on the available evidence there is a significant relationship in glycemic control and cognitive impairment in the AM with DT2, also a lower performance in functional mobility and verbal fluency.Objetivo: Revisar la evidencia disponible que demuestre la relación que existe entre el control glucémico, función cognitiva y las funciones ejecutivas en el AM con DT2.  Métodos: La búsqueda de la literatura se realizó en idioma inglés y español, en 14 bases de datos, Open acces, y en el buscador Google. En base al modelo propuesto por Cooper (2007), para la síntesis de la literatura. Los estudios fueron evaluados para su validez, a través de la guía CASPe para estudios de casos y controles. Resultados: Se analizaron 11estudios de correlación, el 100% de los estudios mostró relación del control glucémico con el deterioro cognitivo y la función ejecutiva en AM con DT2. Los estudios concuerdan que los AM con DT2 presentan deterioro cognitivo, comparado con los AM sin DT2, por lo tanto existe déficit en el AM al realizar las funciones ejecutivas.Conclusiones: Según la evidencia disponible existe una relación significativa en el control glucémico y el deterioro cognitivo en el AM con DT2, así mismo un menor desempeño en la movilidad funcional y la fluidez verbal