High spatial resolution investigation of spin crossover phenomena using scanning probe microscopies

Récemment, un grand nombre d'objets de taille nanométrique, incluant les nanoparticules, les films minces, les dispositifs nanostructurés, présentant des phénomènes de commutation impliquant différents états de spin, ont été développé pour des applications dans le domaine des capteurs et des systèmes nanophotoniques, nanoélectroniques et nanomécaniques. En effet, Ces nanomatériaux à conversion de spin présentent une dépendance en taille des propriétés physico-chimiques très intéressantes. Même si l'origine du phénomène de conversion de spin est purement moléculaire, le comportement macroscopique de ces systèmes à l'état solide est fortement influencé par les interactions intermoléculaires élastiques. On s'attend donc à ce que les propriétés coopératives et, de manière plus générale, le diagramme de phase, soient très dépendantes de la taille du système. Au-delà de la stabilité des phases, les cinétiques de transformation dépendent également de la taille du système. Dans ce contexte, des interactions élastiques fortes conduisent dans de nombreux cas à des transitions de type premier ordre accompagnées par une séparation de phase hétérogène. Les détails du mécanisme de la dynamique spatio-temporelle associée à la transition de spin restent encore inexplorés. L'ensemble de ces phénomènes observés dans les matériaux à transition de spin demande des méthodes de caractérisation possédant une capacité d'imagerie d'une grande résolution spatiale afin d'aller au-delà des techniques de microscopie optique en champ lointain habituellement employées. Par conséquence, l'objectif global de cette thèse de doctorat est de développer de nouvelles approches qui permettent de détecter le phénomène de transition de spin avec une résolution spatiale nanométrique. Pour observer la transition de spin thermique dans les films minces, nous avons utilisé pour la première fois la microscopie optique en champ proche (NSOM en Anglais) ainsi que la microscopie à force atomique (AFM en Anglais) en conjonction avec des dispositifs originaux de chauffage à l'échelle du nanomètre, conçus à partir de nanofils et fonctionnant par effet Joule. En utilisant ces techniques, le changement de l'état de spin a pu être observé avec une résolution sub-longueur d'onde au travers des changements des propriétés mécanique et optique des matériaux. Le NSOM en mode illumination, utilisé soit en luminescence ou en mode réflexion fournit un signal utile pour la détection du changement d'état de spin mais ne permet en revanche qu'une quantification limitée du phénomène en raison de l'instabilité des échantillons (photoblanchiment, ...) . D'un autre côté, les différents modes mécaniques AFM, incluant la spectroscopie à force rapide et l'analyse multifréquentielle, ont permis des mesures quantitatives et reproductibles avec une résolution nanométrique. En particulier, nous avons été capable de mesurer pour la première fois l'augmentation du module d'Young (env. 25-30%) observée lors de la transition de l'état Haut Spin vers l'état Bas Spin et nous avons utilisé cette propriété pour réaliser une imagerie quantitative de la transition de spin. Des mesures AFM ont été faites sur des monocristaux à transition de spin. Nous avons montré que les transferts thermiques entre la sonde et l'échantillon peuvent être utilisés pour manipuler la nucléation et la propagation des phases Haut et Bas Spin dans des cristaux. Par ailleurs, ces interactions sonde-échantillon rendent difficiles l'imagerie AFM de ces phénomènes. Néanmoins, les changements d'ordre topographique de la surface au cours de la transition de spin peuvent être observés et discutés en conjonction avec les résultats de spectroscopie Raman (cartographie) et microscopie optique en champ lointain. L'ensemble de ces résultats ouvre de nouvelles possibilités d'étude et de contrôle/manipulation de ces objets bistables à l'échelle du nanomètreRecently a variety of nanoscale objects, including nanoparticles, thin films and nanometric assemblies, exhibiting molecular spin-state switching phenomena have been developed for applications in sensors, nanophotonic, nanoelectronic and nanomechanical systems. These spin crossover nanomaterials have been also reported to exhibit interesting size-dependent properties. Indeed, even if the origin of the spin crossover phenomenon is purely molecular, the macroscopic behavior of these systems in the solid state is strongly influenced by elastic interactions between the molecules. These cooperative properties and, in general, the phase diagram are expected to depend strongly on the size of the material. Beyond the phase stability, the transformation kinetics is likely to display also size dependence. Indeed, the strong elastic interactions in these materials lead, in many cases, to first-order phase transitions and phase separation phenomena. Details of the associated spatio-temporal dynamics of spin crossover systems remain largely unexplored. All these size dependent and spatially heterogeneous phenomena in spin crossover materials call for appropriate characterization methods with high spatial resolution imaging capability, but to date only far-field optical microscopy has been used to this aim. Hence, the overall objective of this PHD thesis was to develop new approaches allowing to trigger and detect the spin crossover phenomenon with nanometric spatial resolution. For the detection of the thermally induced spin crossover in thin films, we used for the first time Near-Field Scanning Optical Microscopy (NSOM) and Atomic Force Microscopy (AFM) in conjunction with an original nano-heater device, based on Joule-heated metallic nanowires. Using these techniques the spin-state change in the films was inferred with sub-wavelength resolution through the associated optical and mechanical property changes of the material. Apertured NSOM used either in luminescence or reflectivity mode provided useful signal for detecting the spin-state switching phenomena, but rather limited quantification was possible due to sample stability issues (photobleaching, etc). On the other hand, AFM mechanical modes, including fast force spectroscopy and multifrequency analysis, allowed for quantitative and well-reproducible measurements with nanometric resolution. In particular, we have measured for the first time the increase of the Young's modulus (ca. 25-30 %) when going from the high spin to the low spin state and used this property for quantitative imaging of the spin transition. AFM measurements were also performed on spin crossover single crystals. We have shown that probe-sample thermal interactions can be used to manipulate the nucleation and propagation of the high spin and low spin phases in the crystals. On the other hand, these interactions make for difficulties for the AFM imaging of these phenomena. Nevertheless changes of the surface topography during the spin transition can be observed and discussed in conjunction with far-field optical microscopy and Raman spectroscopy data. The ensemble of these results open up new possibilities for the investigation and manipulation of these bistable objects at the nanoscale

Evaluation of The Inter-Batch Variability of An Active Pharmaceutical Ingredient: Morphologic, Rheologic And Calorimetric Characterization

Beca nacional Edna Teresa Alcantara Fierro PEI 2015/220172All raw materials used for solid oral drugs manufacturing must be evaluated according to the pharmacopoeial monographs, which consist in a verification of critical quality attributes related to the identity and purity of the molecule. However, active pharmaceutical ingredients may present differences in non-pharmacopoeial tests, such as particle size and shape or flow. Although these differences are not evaluated routinely by Quality Control area, they can alter the technological performance during production, as well the stability and ultimately the efficacy of a pharmaceutical product. In this study, 10 production batches of magnesium valproate were evaluated, characterizing flow index, fusion enthalpy and particle shape and size distribution. An analysis of variance was carried out, finding statistically-significant differences in the flow index, particle shape and fusion enthalpy tests for two batches. These differences may be due to small variations in the crystalline configurations. The study showed differences in the characterization of fundamental and functional properties of the particles of the active pharmaceutical ingredient evaluated, which could have an impact on the manufacturing processes and affect therapeutic efficacy.CONACY

From Porciones to Colonias: Curriculum Development in K-12 Education--Methodology and Program Development

The 2012 National Endowment for the Humanities- sponsored “From Porciones to Colonias: Inserting the “Hispanic” in a Hispanic Serving Institution through Curriculum Innovation” brought together faculty at the largest Hispanic Serving Institution in Texas, the University of Texas-Pan American (UTPA), and public school teachers to create place-based curriculum. Using the natural landscape and cultural history of one of the most dynamic borderlands in the world as the main classroom laboratory, faculty housed in the CHAPS program (Community Historical Archaeology Project with Schools) challenged elementary, middle, and high school teachers in the sciences, social sciences and humanities to create in their students historically literate citizens who are aware of their local cultural and natural history. The following briefly encapsulates the conducted activities

Desarrollo de un cuestionario de evaluación de la competencia docente en línea

Evaluating teaching to improve the quality of education implies to recognize its complexity and to count with valid assessment instruments that lead to improvement. The objective of this article is to report the research process that allowed the development of a formative assessment questionnaire of on-line teaching based on the opinion of students. The participants were six experts on the design and implementation of on-line courses, and a total of 2821 university students. The method consisted of two stages: 1) Development of the instrument through theoretical background regarding the elements of the on-line teaching competencies that are susceptible of being evaluated by students; the making of the questionnaire specification matrix; matrix validation by experts judgment and pilot study; 2) Contribution of confidence evidence and validity included the application of the questionnaire; descriptive statistical calculations; unidimensional analysis through the Rasch model; establishment of the scores reliability; exploratory and confirmatory factorial analysis. It was demonstrated that 28 items evaluate the same construct and 2 factors were confirmed: forecast of the teaching-learning process and the conduction and evaluation of the teaching and learning experience; a total variance of 0.01% and alpha ordinal of 0.998; and adjustment index RMSEA=0.08; SRMR= 0.03, CF1=0.91. It was concluded that the results corroborated the instrument’s theoretical background with acceptable psychometric characteristics so that its application is recommended.Evaluar la docencia con el fin de mejorar la calidad de la enseñanza implica reconocer su complejidad y contar con instrumentos de evaluación válidos que orienten hacia la mejora. El objetivo de este artículo es reportar el proceso de investigación que permitió desarrollar un cuestionario de evaluación formativa de la docencia en línea con base en la opinión de los estudiantes. Los participantes fueron seis expertos en el diseño e implementación de cursos en línea y un total de 2821 estudiantes universitarios. El método consistió en dos etapas: 1) Desarrollo del instrumento a través de fundamentación teórica sobre los elementos de la competencia docente en línea susceptibles de ser evaluados por estudiantes; elaboración de la matriz de especificación del cuestionario; validación de la matriz por el juicio de expertos y estudio piloto; 2) Aportación de evidencias de confiabilidad y validez incluyó la aplicación del cuestionario; cálculo de estadísticos descriptivos; análisis de unidimensionalidad por medio del modelo Rasch; determinación de la confiabilidad de los puntajes; análisis factorial exploratorio y confirmatorio. Se demostró que 28 reactivos evalúan el mismo constructo y se confirmaron dos factores: previsión del proceso de enseñanza y aprendizaje; y conducción y evaluación de la experiencia de enseñanza y aprendizaje; una varianza total de 70.01% y alpha ordinal de .998; un índice de ajuste RMSEA= .08, SRMR= .03, CFI= .91. Se concluye que los resultados corroboraron el fundamento teórico del instrumento con características psicométricas aceptables, por lo que se recomienda su aplicación

a case–control study

Objectives: To determine the association between Toxoplasma gondii infection and Parkinson's disease and to investigate whether T. gondii seropositivity is associated with the general characteristics of patients with Parkinson's disease. Design Case–control study. Setting: Cases and controls were enrolled in Durango City, Mexico. Participants: 65 patients with Parkinson's disease and 195 age- and gender-matched control subjects without Parkinson's disease. Primary and secondary: outcome measures Serum samples of participants were analysed for anti-T. gondii IgG and IgM antibodies by commercially available enzyme-linked immunoassays. Prevalence of T. gondii DNA was determined in seropositive subjects using PCR. The association between clinical data and infection was examined by bivariate analysis. Results: Anti-T. gondii IgG antibodies were found in 6/65 cases (9.2%) and in 21/195 controls (10.8%) (OR 0.84; 95% CI 0.32 to 2.18; p=0.81). The frequency of high (>150 IU/mL) antibody levels was similar among cases and controls (p=0.34). None of the anti-T. gondii IgG positive cases and four of the anti-T. gondii IgG positive controls had anti-T. gondii IgM antibodies (p=0.54). The prevalence of T. gondii DNA was comparable in seropositive cases and controls (16.7% and 25%, respectively; p=1.0). Seroprevalence of T. gondii infection was associated with a young age onset of disease (p=0.03), high Unified Parkinson Disease Rating Scale scores (p=0.04) and depression (p=0.02). Seropositivity to T. gondii infection was lower in patients treated with pramipexole than in patients without this treatment (p=0.01). However, none of the associations remained significant after Bonferroni correction. Conclusions: The results do not support an association between T. gondii infection and Parkinson's disease. However, T. gondii infection might have an influence on certain symptoms of Parkinson's disease. Further research to elucidate the role of T. gondii exposure on Parkinson's disease is warranted

Stenocarpella maydis and Sporisorium reilianum: Two Pathogenic Fungi of Maize

Stenocarpella maydis and Sporisorium reilianum are phytopathogenic fungi that cause white rot in corn cob and head smut in maize (Zea mays L.) respectively, diseases that are spread worldwide and cause many economic losses. In this chapter the characteristics of the above diseases, such as their life cycle, pathogenicity factors, control methods, as well as the biotechnological potential of the fungi involved in this processes are described, specifically in connection to their extracellular enzymes

Identifying nonalcoholic fatty liver disease patients with active fibrosis by measuring extracellular matrix remodeling rates in tissue and blood.

Excess collagen synthesis (fibrogenesis) in the liver plays a causal role in the progression of nonalcoholic fatty liver disease (NAFLD). Methods are needed to identify patients with more rapidly progressing disease and to demonstrate early response to treatment. We describe here a novel method to quantify hepatic fibrogenesis flux rates both directly in liver tissue and noninvasively in blood. Twenty-one patients with suspected NAFLD ingested heavy water (2 H2 O, 50-mL aliquots) two to three times daily for 3-5 weeks prior to a clinically indicated liver biopsy. Liver collagen fractional synthesis rate (FSR) and plasma lumican FSR were measured based on 2 H labeling using tandem mass spectrometry. Patients were classified by histology for fibrosis stage (F0-F4) and as having nonalcoholic fatty liver or nonalcoholic steatohepatitis (NASH). Magnetic resonance elastography measurements of liver stiffness were also performed. Hepatic collagen FSR in NAFLD increased with advancing disease stage (e.g., higher in NASH than nonalcoholic fatty liver, positive correlation with fibrosis score and liver stiffness) and correlated with hemoglobin A1C. In addition, plasma lumican FSR demonstrated a significant correlation with hepatic collagen FSR.ConclusionUsing a well-characterized cohort of patients with biopsy-proven NAFLD, this study demonstrates that hepatic scar in NASH is actively remodeled even in advanced fibrosis, a disease that is generally regarded as static and slowly progressive. Moreover, hepatic collagen FSR correlates with established risks for fibrotic disease progression in NASH, and plasma lumican FSR correlates with hepatic collagen FSR, suggesting applications as direct or surrogate markers, respectively, of hepatic fibrogenesis in humans. (Hepatology 2017;65:78-88)

IMPACTO DE LA POLÍTICA PÚBLICA EQUIDAD DE GÉNERO CON ENFOQUE EN LAS MUJERES RURALES DE FLORENCIA - CAQUETÁ

Este artículo presenta una revisión bibliográfica de lo que es la política pública de equidad de géneroen Colombia, enfocando su análisis en el estado de la mujer en el sector rural, en especial en elmunicipio de Florencia. Para el desarrollo del presente artículo de revisión documental, se ha tomadocomo referente algunos sustentos teóricos que han permitido analizar la evolución significativa del papelrelevante que juega la mujer en la construcción de sociedad, en especial la mujer rural. Según lo planteadopor Abramo (2006), para que las mujeres puedan insertarse de manera satisfactoria en el mercado laboral y,adicionalmente, cuenten con las condiciones necesarias para competir en igualdad frente a los hombres, sehacen necesarias medidas adicionales al marco legal. Es de vital importancia implementar accionesafirmativas que permitan aumentar sus posibilidades de acceso al trabajo remunerado y oportunidadesde generación de ingresos, disminuir la invisibilidad del trabajo realizado en diversas esferas noreconocidas.Para la Organización de Estados Americanos OEA (2011), la importancia de generar accionesafirmativas con enfoque de género, no solo se enmarca dentro de un discurso de defensa y promociónde los derechos humanos, sino también, dentro de un discurso de desarrollo y crecimiento económico. En lamedida que los países tengan una mayor igualdad entre mujeres y hombres, serán más productivos ytendrán mayores niveles de crecimiento económico, una institucionalidad más representativa y mejoresresultados de desarrollo para las próximas generaciones. El artículo No. 19 del Código de Ética Profesionalpara los Administradores de Empresas, establece: “Que se debe tomar parte activa en las decisiones yproblemáticas de la localidad donde trabaja y de la nación en general, buscando soluciones a las causascívicas y de servicio comunitario”. (Acuerdo 003 de 1987. Ministerio de Comercio, Industria y Turismo).Con lo anteriormente expuesto, las reflexiones del presente artículo, permitirá que desde laprofesión de Administrador de Empresas, se pueda dar respuestas a los problemas y necesidadessociales, educativas, ambientales, culturales y productivas que aquejan a la mujer rural en elmunicipio de Florencia-Caquetá.Palabras Clave: Igualdad, Género, Leyes, Muje

Inteligencia emocional y estrés en adultos con y sin tratamiento contra la adicción al alcohol y drogas

analizar la relación de la inteligencia emocional (IE) y el estrés percibido (EP) en un grupo de hombres consumidores de alcohol y drogas en comparación con un grupo de no consumidores. Método: diseño transversal de casos y controles. La muestra estuvo formada por 35 adultos dependientes a las drogas y 35 adultos sin problemas de consumo. El rango de edad fue de 18 a 61 años. La muestra fue recogida por medio de una selección intencional, no probabilística. Se utilizó el Inventario de Inteligencia Emocional (EQ-I) y la Escala de Estrés Percibido (CEP). Resultados: los datos muestran correlaciones significativas entre la IE y el EP en el último año (r = -.317, p < .01), así como diferencias significativas entre los dos grupos, siendo la IE inferior en los adultos del grupo consumo con alto EP (U=-3.918, p=.000). Conclusión: los hallazgos obtenidos sirven de base para la implementación de estrategias basadas en desarrollar habilidades de IE con la finalidad de disminuir el consumo de alcohol y drogas, fomentar la búsqueda y apego al tratamiento, así como la prevención de recaídas.to analyze the relationship of emotional intelligence (EI) and the perceived stress (PS) in a group of men who consume alcohol and drugs in comparison with a group of non-consumers. Method: cross-sectional design of cases and controls. The sample consisted of 35 drug-dependent adults and 35 adults with no drug use problems. The age range was 18 to 61 years. The sample was collected by means of an intentional selection, not probabilistic. The Emotional Intelligence Inventory (EQ-I) and the Perceived Stress Scale (CEP) were used. Results: the data show significant correlations between EI and PS in the last year (r = -.317, p <.01), as well as differences between the groups, the EI being lower in the adults in the consumption group with high PS (U = -3.918, p = .000). Conclusion: the findings obtained serve as the basis for the implementation of strategies based on developing EI skills in order to decrease consumption of alcohol and drugs, promote the search and adherence to treatment, as well as the prevention of relapses.analisar a relação da inteligência emocional (IE) e estresse percebido (EP) em um grupo de homens consumidores de álcool e drogas em comparação com um grupo de não consumidores. Método: desenho transversal de casos e controles. A amostra foi composta por 35 adultos dependentes de drogas e 35 adultos sem problemas de uso de drogas. A faixa etária foi de 18 a 61 anos. A amostra foi coletada por meio de seleção intencional, não probabilística. Foram utilizados o Inventário de Inteligência Emocional (EQ-I) e a Escala de Estresse Percebido (CEP). Resultados: os dados mostram correlações significativas entre a IE e o PE no último ano (r = -.317, p <.01), bem como diferenças entre os grupos, sendo o IE menor nos adultos no grupo de consumo com alto PE (U = - 3,918, p = 0,000). Conclusão: os achados obtidos servem de base para a implementação de estratégias baseadas no desenvolvimento de habilidades de IE, a fim de reduzir o consumo de álcool e drogas, promover a busca e adesão ao tratamento, bem como a prevenção de recaídas