Eficiencia de una membrana de polipropileno modificada con quitosano en la remoción de iones metálicos ca+2, cu+2, cd+2 y pb+2

En el presente proyecto de investigación se llevó a cabo la evaluación de la eficiencia de una membrana de polipropileno modificada con quitosano en la remoción de iones Ca+2, Cu+2, Cd+2 y Pb+2, se propuso que los iones metálicos se coordinen con los grupos hidroxilo y amino injertados, favoreciendo la remoción de los iones metálicos de la solución acuosa. Se buscaron las condiciones óptimas de modificación de la membrana de polipropileno variando los siguientes parámetros:•El tiempo de reacción •La longitud de onda •La concentración de quitosano. Las membranas modificadas fueron caracterizadas por técnicas analíticas cualitativas como espectroscopía FT-IR-ATR (Infrarrojo con Transformada de Fourier acoplado a reflectancia total atenuada), MEB-EDS (Microscopia Electrónica de Barrido-Espectroscopia de Energía Dispersiva), DRX de polvos (Difracción de Rayos X), XPS (Espectroscopia fotoelectrónica de rayos X).Finalmente, se prepararon soluciones a concentración conocida de Ca+2, Cu+2, Cd+2 y Pb+2, y se evaluó la capacidad de remoción de los iones metálicos, utilizando la membrana modificada como filtro, analizando el filtrado por ICP y Espectrometría de Absorción Atómica.3719 SIYEA Y 220392 CONACY

Rank diversity of languages: Generic behavior in computational linguistics

Statistical studies of languages have focused on the rank-frequency distribution of words. Instead, we introduce here a measure of how word ranks change in time and call this distribution \emph{rank diversity}. We calculate this diversity for books published in six European languages since 1800, and find that it follows a universal lognormal distribution. Based on the mean and standard deviation associated with the lognormal distribution, we define three different word regimes of languages: "heads" consist of words which almost do not change their rank in time, "bodies" are words of general use, while "tails" are comprised by context-specific words and vary their rank considerably in time. The heads and bodies reflect the size of language cores identified by linguists for basic communication. We propose a Gaussian random walk model which reproduces the rank variation of words in time and thus the diversity. Rank diversity of words can be understood as the result of random variations in rank, where the size of the variation depends on the rank itself. We find that the core size is similar for all languages studied

Chemical Investigation of Camu Camu (\u3ci\u3eMyrciaria dubia\u3c/i\u3e) Leaves and Roots

Flores, Jorge L., Chemical Investigation of Camu Camu (Myrciaria dubia) Leaves and Roots. Master of Science (MS), December, 2020, 45 pp., 8 Tables, 28 Figures, 21 references, 12 titles.Being the largest on the planet, the Amazon rainforest also has the greatest biodiversity of plant life on earth. In the lowland regions of the Amazon grows the Peruvian camu camu (Myrciaria dubia) plant. A short and shaggy shrub, camu camu produces a tasty but sour fruit. Camu camu’s berry-like fruit is widely consumed by the native people of the Amazon. Its distinguished richness in vitamin C, as well as the presence of antioxidants, minerals, and nutraceuticals, make it valuable to healthy eating. These qualities have also helped the fruit find their prominence in the international market. Literature shows that the fruit of the camu camu plant has undergone chemical investigation and pharmacological examination, however, the investigation of neither the roots nor the leaves has been carried out in detail. Besides the fruit, various parts of the plant have been shown to be valuable to Amazonian folklore medicine, including the leaves and the roots. In order to identify new sources of medicinally important or industrially valuable compounds from existing but neglected botanicals, a chemical investigation of the non-polar to polar extracts from the camu camu plant have been conducted. Ultra High-Performance Liquid Chromatography (UHPLC-MS) studies have been performed for the polar extracts of both the roots and the leaves; the chemical composition of these plant parts and identification of several medicinally valuable compounds has been accomplished. A Gas Chromatography-Mass Spectrometry (GC-MS) study has been performed for a non-polar fraction from the diethyl ether extract of the leaves; 100 compounds were found to be present, 49 known and 51 currently unknown. The isolation of 4 non-polar compounds has been carried out via column chromatography of the same diethyl ether leaf extract; Fourier-Transform Infrared Spectroscopy (FTIR) analysis has been conducted and the compounds have been determined to be pure. This study begins to uncover the privileged molecules from the camu camu plant’s leaves and roots that may create useful applications for this untapped yet abundant natural resource

Women in Computer Science

For this week’s unit, Gender at work, I chose to focus my investigation on gender in the computing industry. More specifically, the goal of my research was to uncover some of the reasons behind the lack of female representation in the computer science world. As a minority in computer science, this investigation has been very personal to me because it has allowed me to learn more about some of the institutional oppressors that have been adopted over time to further marginalize minority populations and allow a certain demographic to flourish. As you may have learned from our previous discussions and explorations in Sociology, that demographic is the average white, able-bodied, Christian male. I have reviewed a plethora of scholarly articles and have made note of some of the frequent themes that have led to the lack of female representation in computer science, and have compiled all these claims and conversations into this presentation. My findings have been astonishing, to say the least, and I am happy to share this information with you in the slides to come.https://digitalcommons.tacoma.uw.edu/gender_studies/1064/thumbnail.jp

Taxon incompleteness and discrete time bins affect character change rates in simulated data

Estimating how fast or slow morphology evolves through time (phenotypic change rate, PR) has become common in macroevolutionary studies and has been important for clarifying key evolutionary events. However, the inclusion of incompletely scored taxa (e.g. fossils) and variable lengths of discrete arbitrary time bins could affect PR estimates and potentially mask real PR patterns. Here, the impact of taxon incompleteness (unscored data) on PR estimates is assessed in simulated data. Three different time bin series were likewise evaluated: bins evenly spanning the tree length (i), a shorter middle bin and longer first and third bins (ii), and a longer middle bin and shorter first and third bins (iii). The results indicate that PR values decrease as taxon incompleteness increases. Statistically significant PR values, and the dispersion among PR values, depended on the time bins. These outcomes imply that taxon incompleteness can undermine our capacity to infer morphology evolutionary dynamics and that these estimates are also influenced by our choice of discrete time bins. More importantly, the present results stress the need for a better approach to deal with taxon incompleteness and arbitrary discrete time bins.Peer reviewe

La enseñanza se la probabilida “ser saber sabio al saber enseñado”

El aprendizaje de la unidad de probabilidad, en un curso de estadística, presenta serias dificultades a los estudiantes, al momento de resolver problemas. Entre los factores que pueden mencionarse están: 1) las concepciones alternativas que impiden la comprensión del concepto de probabilidad y sus reglas, por ejemplo, la dificultad para determinar si dos eventos son independientes (Serrado, Cardeñoso y Azcarate, 2005); 2) la utilización de conceptos, símbolos y gráficos matemáticos que aunque son familiares para el estudiante en el dominio de la lógica matemática, su transferencia al dominio de la Probabilidad se ve limitada por el aprendizaje superficial que ellos realizan; 3) la enseñanza de los conceptos y reglas de la probabilidad, desde la perspectiva del“saber sabio”y no desde la perspectiva del “saber enseñado”; no permite a los estudiantes comprender el concepto de probabilidad y sus conceptos relacionados; este último factor implica, que el profesor para que los estudiantes comprendan los conceptos y reglas de la probabilidad, tiene que transformar el conocimiento científico (“saber sabio”) en una forma de conocimiento (“saber enseñado”) que sea accesible a ellos. Por otro lado, dado que la probabilidad es una ciencia axiomática, los conceptos básicos se pueden enseñar a los estudiantes de manera intuitiva, utilizando objetos asociados con este problema (monedas, dados, fichas, bolas, etc.). En consecuencia, el propósito de este estudio fue mejorar el rendimiento de los estudiantes aplicando la transposición didáctica en la enseñanza de probabilidad

Revolute joints with clearance in multibody systems

A computational methodology for dynamic analysis of multibody mechanical systems with joint clearance is presented in this work. Clearances always exist in real joints in order to ensure the correct relative motion between the connected bodies being the gap associated to them a result of machining tolerance, wear, and local deformations. Clearance at different joints is the source for impact forces, resulting in wear and tear of the joints, and consequently the degradation of the system performance. The model for planar revolute joints is based on a thorough geometric description of contact conditions and on a continuous contact force model, which represents the impact forces. It is shown that the model proposed here lead to realistic contact forces. These forces correlate well with the joint reaction forces of an ideal revolute joint, which correspond to a null joint clearance. The application to the analysis of a simple planar multibody system illustrates the use of the different models proposed.Fundação para a Ciência e a Tecnologia (FCT