Estudio de la oxidación de metanol sobre catalizadores Au@ Ptx núcleo-envolvente utilizando espectroscopia de impedancia electroquímica

90 páginas. Maestría en Ciencias e Ingeniería de Materiales.El acelerado consumo de los combustibles fósiles así como su impacto ambiental, ha llevado a buscar formas alternativas de energía tal es el caso de las celdas de combustible que presentan eficiencias de hasta el 60% y además son amigables con el medio ambiente. De particular interés las de metanol directo (DMFC), ya que el metanol es fácil de manejar transportar y es económicamente viable; sin embargo presentan algunos inconvenientes que limitan su aplicación: la reacción de oxidación de metanol (MOR) presenta una cinética lenta, por ello se emplea patino (Pt) como catalizador el inconveniente del Pt es su elevado costo y su susceptibilidad al envenenamiento por CO, uno de los intermediarios de reacción. En este trabajo se evalúa la actividad catalítica de nanopartículas (NPs) de Pt y del tipo core-shell, núcleo de oro y envolvente variable de platino soportados en carbón Vulcan XC-72R para la MOR. Para la caracterización física se empleó espectroscopia Ultravioleta-Visible (Uv-Vis), Difracción de Rayos X (DRX) y microscopia electrónica de barrido-transmisión (STEM), se encontró que las NPs presentan estructura cristalina, forma cuasi-esférica, con una dispersión de tamaño uniforme. A través Voltamperometria Cíclica (VC) y Cronoamperometría (CA) se encontró que el catalizador Au@Pt1/C presenta el mejor comportamiento para la MOR. Debido a que la Espectroscopia de Impedancia Electroquímica (EIS) permite separar distintas contribuciones electroquímicas que ocurren durante la MOR, y a través del ajuste de los espectros mediante circuitos equivalentes (utilizados para modelar la respuesta de impedancia) se obtuvieron parámetros como: Rtc, R1 y R2, asociadas a las resistencias de distintos procesos, en donde la respuesta de cada una de éstas se ve influenciada por el tipo de catalizador, así como del potencial aplicado.Consejo Nacional de Ciencia y Tecnología (México)

Reversal Flow in Fixed-Bed Reactors Operating Under Reaction-Regeneration Cycles

The unsteady state simulation of a set of industrial fixed-bed reactors is presented. The catalytic dehydrogenation of 1-butene into 1-3-butadiene is selected as case study. These reactors operate under reaction-regeneration cycles. Each stage of the process, i.e., dehydrogenation (deactivation by coking), steam purge, oxidative regeneration and evacuation, is simulated by means of the corresponding dynamic model. The kinetic parameters used in the dehydrogenation and regeneration stages for a Cr2O3/Al2O3 catalyst are taken from the literature. The performance of the reactors is investigated for two different operation modes: conventional (CO) and periodic flow reversal (PRFO). The PRFO mode shows significantly lower values for the average bed temperature and residual coke concentrations than those corresponding to the CO mode. This behaviour has a favourable effect on the production rate of butadiene. In addition, the influence of the catalyst sintering is analysed in this paper for both operation modes. The deactivation rate by thermal degradation is lower in the case of PRFO due to the lower average temperature of the catalyst bed. Periodic flow reversal strategies provide an economical and efficient alternative to optimise cyclic processes

A review of explicit and implicit assumptions when providing personalized feedback based on self-report EMA data

Ecological Momentary Assessment (EMA) in which participants report on their moment-to-moment experiences in their natural environment, is a hot topic. An emerging field in clinical psychology based on either EMA, or what we term Ecological Retrospective Assessment (ERA) as it requires retrospectivity, is the field of personalized feedback. In this field, EMA/ERA-data-driven summaries are presented to participants with the goal of promoting their insight in their experiences. Underlying this procedure are some fundamental assumptions about (i) the relation between true moment-to-moment experiences and retrospective evaluations of those experiences, (ii) the translation of these experiences and evaluations to different types of data, (iii) the comparison of these different types of data, and (iv) the impact of a summary of moment-to-moment experiences on retrospective evaluations of those experiences. We argue that these assumptions deserve further exploration, in order to create a strong evidence-based foundation for the personalized feedback procedure

As tecnologias e a forma??o de professores dos anos iniciais da educa??o b?sica no Paraguai e Brasil : distanciamentos e aproxima??es.

Programa de P?s-Gradua??o em Educa??o. Departamento de Educa??o, Instituto de Ci?ncias Humanas e Sociais, Universidade Federal de Ouro Preto.Esta investiga??o cient?fica teve como objetivo principal o intuito de analisar os distanciamentos e aproxima??es em rela??o ?s contribui??es das tecnologias na contemporaneidade para a forma??o de professores dos Anos Iniciais da Educa??o B?sica no Paraguai e Brasil por meio da percep??o de professores formadores e futuros professores. Para tal, a pesquisa se pautou em uma revis?o junto ? literatura espec?fica que versa sobre a tem?tica, atrelada por uma pesquisa de campo que foi realizada com professores e alunos que se disponibilizaram participar voluntariamente de uma Institui??o p?blica de forma??o de professores, localizada no Paraguai e outra no Brasil, sendo que os sujeitos desta pesquisa foram vinte professores/as e vinte alunos/as dos Cursos de Pedagogia, que responderam um question?rio, al?m desse instrumento foi tamb?m realizada uma entrevista com cinco docentes e cinco discentes de cada pa?s para aquisi??o de informa??es sob o intuito de que os dados pudessem melhor consubstanciar nossas an?lises e reflex?es, sobre como a forma??o de professores lida com os distanciamentos e aproxima??es em rela??o as tecnologias na forma??o docente em ambos os pa?ses. Os dados demonstraram que os professores nos dois pa?ses em quest?o se sentem desafiados a buscar informa??es que ultrapassam a dimens?o de apenas informar em termos do conhecimento produzido sobre o mundo, o que direciona o olhar para si mesmo sobre o modo de ensinar e aprender de modo cr?tico por meio das tecnologias.The main objective of this scientific investigation was to analyze the distances and approximations in relation to the contributions of contemporary technologies to the formation of teachers of the early years of basic education in Paraguay and Brazil through the perception of teacher trainers and future teachers. To this end, the research was based on a review of the specific literature on the subject, coupled with a field research that was conducted with teachers and students who volunteered to participate in a public teacher training institution, located in Paraguay. and another in Brazil, and the subjects of this research were fifteen teachers and twenty students from the Pedagogy Courses, who answered a questionnaire. In addition to this instrument, an interview was also conducted with five teachers and five students from each country for acquisition. of information in order that the data could better substantiate our analyzes and reflections on how teacher education deals with distances and approximations in relation to technologies in teacher education in both countries. The data showed that teachers in the two countries in question feel challenged to seek information that goes beyond just informing in terms of the knowledge produced about the world, which directs the view to oneself on how to teach and learn critical through technologies

Joint tumor bud–MMP/TIMP count at the invasive front improves the prognostic evaluation of invasive breast carcinoma

Producción CientíficaBackground: Tumor budding is a histological phenomenon consisting of the formation of small clusters of one to five undifferentiated malignant cells detached from the main tumor mass which are observed in the tumor stroma. In the present study, we investigated the prognostic significance of tumor budding in breast cancer and its relationship with the expressions of matrix metalloproteases (MMPs) and their tissue inhibitors (TIMPs). Methods: The number of buds was counted in whole-tissue sections from 153 patients with invasive ductal carcinomas who underwent a long follow-up period. In addition, an immunohistochemical study of MMP-9, -11, and -14 TIMP-1 and -2 expression by cell types at the invasive tumor front was carried out. Results: There was a wide variability in the number of buds among tumors, ranging from 0 to 28 (median = 5). Tumor budding count ≥ 4 was the optimal cut-off to predict both relapse-free and overall survival. High-grade tumor budding was associated with MMP/TIMP expression by cancer-associated fibroblasts. In addition, we found that the combination of tumor budding grade with MMP/TIMP expression by stromal cells, and especially with MMP-11 expression by mononuclear inflammatory cells, significantly improved the prognostic evaluation. Conclusion: High-grade tumor budding is associated with a more aggressive tumor phenotype, which, combined with MMP/TIMP expression by stromal cells at the invasive front of the tumor, identifies patients with poor prognosis.Instituto de Salud Carlos III y Fondo Europeo de Desarrollo Regional (FEDER) - (grant PI17/02236 and DTS19-00109

SEOM clinical guidelines for the treatment of non‑small cell lung cancer (2018)

Non-small cell lung cancer (NSCLC) accounts for up to 85% of all lung cancers. The last few years have seen the development of a new staging system, diagnostic procedures such as liquid biopsy, treatments like immunotherapy, as well as deeper molecular knowledge; so, more options can be offered to patients with driver mutations. Groups with specific treatments account for around 25% and demonstrate significant increases in overall survival, and in some subgroups, it is important to evaluate each treatment alternative in accordance with scientific evidence, and even more so with immunotherapy. New treatments similarly mean that we must reconsider what should be done in oligometastatic disease where local treatment attains greater valu

The Quality of Life and Experiences of Tertiary Education Subsidy (TES) Grantees

In the past years, many students had problems with their finances, especially their expenses for education. Many of the students are affected by the crisis financially, emotionally, and by their wellbeing. That is why the government provides programs that will help the students with their problems with school expenses, and that is through the Tertiary Education Subsidy (TES) of the Commission on Higher Education (CHED). Further, the primary goal of this study is to explore the TES Grantees' lived experiences, challenges, and coping mechanisms. Furthermore, these are the study's findings: (1) The grantees find the TES very helpful regarding finances that will tackle their academic needs, such as tuition fees and school learning materials. (2) Many students value government assistance that motivates them to maintain their grades

Pharmacological sequestration of mitochondrial calcium uptake protects against dementia and β-amyloid neurotoxicity

All forms of dementia including Alzheimer's disease are currently incurable. Mitochondrial dysfunction and calcium alterations are shown to be involved in the mechanism of neurodegeneration in Alzheimer's disease. Previously we have described the ability of compound Tg-2112x to protect neurons via sequestration of mitochondrial calcium uptake and we suggest that it can also be protective against neurodegeneration and development of dementia. Using primary co-culture neurons and astrocytes we studied the effect of Tg-2112x and its derivative Tg-2113x on β-amyloid-induced changes in calcium signal, mitochondrial membrane potential, mitochondrial calcium, and cell death. We have found that both compounds had no effect on β-amyloid or acetylcholine-induced calcium changes in the cytosol although Tg2113x, but not Tg2112x reduced glutamate-induced calcium signal. Both compounds were able to reduce mitochondrial calcium uptake and protected cells against β-amyloid-induced mitochondrial depolarization and cell death. Behavioral effects of Tg-2113x on learning and memory in fear conditioning were also studied in 3 mouse models of neurodegeneration: aged (16-month-old) C57Bl/6j mice, scopolamine-induced amnesia (3-month-old mice), and 9-month-old 5xFAD mice. It was found that Tg-2113x prevented age-, scopolamine- and cerebral amyloidosis-induced decrease in fear conditioning. In addition, Tg-2113x restored fear extinction of aged mice. Thus, reduction of the mitochondrial calcium uptake protects neurons and astrocytes against β-amyloid-induced cell death and contributes to protection against dementia of different ethology. These compounds could be used as background for the developing of a novel generation of disease-modifying neuroprotective agents

Electro oxidación de metanol sobre catalizadores Au@Ptx/C y Pt/C mediante potenciales de inversión

En este trabajo se sintetizaron nanopartículas (NPs) del tipo núcleo envolvente soportadas en carbón Vulcan (Au@Ptx/C) con distintas relaciones de Pt en el envolvente (x=0.2, 0.5 y 1 relación atómica con respecto Au) para evaluar su actividad en la reacción de oxidación de metanol (MOR), teniendo como sistema de referencia NPs de Pt/C. Se encontró que el catalizador Au@Pt1/C favorece la MOR, lo anterior se asocia a la presencia del núcleo de oro en la estructura lo cual debilita el enlace Pt-COads evitando la desactivación del catalizador. Adicionalmente, se estudió la influencia del potencial de inversión de -0.2 a 1.4 V vs SCE, con el propósito de evaluar el cociente de la densidad de corriente de los picos asociados a la MOR durante el barrido de ida y el de regreso (jf/jb ), ya que en la literatura el cociente se asocia con la tolerancia del catalizador al CO, sin embargo se observó que el cociente jf/jb depende del límite de potencial anódico.In this work, core-shell type nanoparticles (NP) supported on carbon Vulcan (Au@ Ptx/C) were synthesized with different Au to Pt ratios (x=0.2, 0.5 and 1 atomic ratio with respect to Au) for the methanol oxidation reaction (MOR) evaluation, having as reference system Pt/C NPs. It was found that Au@Pt1/C catalyst favors the MOR, this was associated to the presence of gold-core in the structure, which weakens Pt-COads bond, preventing catalyst from deactivation. In addition, the influence of inversion potential from -0.2 to 1.4 V vs SCE was studied, with the purpose of assessing the ratio of current density of the forward and backward peaks associated to the MOR (jf/jb), in the literature it is associated to the catalyst´s CO-tolerance, however it was observed that the ratio jf/jb depends on the limit of the anodic potential