Preparation, characterization, intrinsic dissolution studies and microbiological assessment of dapsone tosylate polymorphs

Purpose: To prepare dapsone tosylate salt (TD) and its two polymorphs (TD-I and TD-II), and study their intrinsic dissolution profiles and preliminary anti-mycobacterium activity.Methods: The synthesized product was studied with respect to the effect of solvent selection, reaction temperature and evaporation rate on the solid phase obtained. The polymorphs were characterized using powder x-ray diffraction (PXRD), proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). UV/Vis spectroscopy was employed for quantification of the salt, while Wood apparatus was used for dissolution studies. Microdilution assay, using a 96-well equipment, was employed for the evaluation of anti-mycobacterial activity.Results: On analysis of the solids obtained from synthesis with PXRD, two different patterns were observed. One pattern belonged to TD-I, previously reported, and the other was a new polymorph TD-II. Solvent evaporation was important in the selective preparation of TD-I or TD-II. Analyses with DSC, TGA and 1H-NMR revealed the absence of solvent in both solids and showed that TD-II was not a solvated salt. Spectral analysis with FT-IR demonstrated structural relationship between TD-I and TD-II. Intrinsic dissolution studies showed that both polymorphs dissolved faster than dapsone (DAP).Conclusion: It is possible to synthesize TD and select the polymorph prepared by means of modulated solvent evaporation rate. The rank order of the intrinsic dissolution rate constants was TD-II > TD-I > DAP. The tosylate salt enhanced inhibitory effect on M. fortuitum, when compared to DAP.Keywords: Dapsone tosylate, Polymorphism, Solid phase characteristics, Intrinsic dissolution, Antimycobacterium activit

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans – anteaters, sloths, and armadillos – have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with 24 domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, ten anteaters, and six sloths. Our dataset includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data-paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the south of the USA, Mexico, and Caribbean countries at the northern portion of the Neotropics, to its austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n=5,941), and Cyclopes sp. has the fewest (n=240). The armadillo species with the most data is Dasypus novemcinctus (n=11,588), and the least recorded for Calyptophractus retusus (n=33). With regards to sloth species, Bradypus variegatus has the most records (n=962), and Bradypus pygmaeus has the fewest (n=12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other datasets of Neotropical Series which will become available very soon (i.e. Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans dataset

Desarrollo e implementación de un módulo didáctico de automatización bajo una red de comunicación industrial Modbus

Este trabajo presenta el desarrollo y la implementación de un módulo didáctico bajo una red de comunicación con protocolo Modbus RTU, integrando elementos de automatización industrial como lo son una interfaz gráfica (HMI), dos controladores lógicos programables PLC’s y un variador de frecuencia altivar 71. La red de comunicación industrial implementada, alcanzó una máxima transferencia de datos en el orden de 19200 kbit/s, lo cual permitió desde un dispositivo maestro tener la capacidad de acceso, control y tratamiento a todos los registros internos de memoria de sus dispositivos esclavos. El desarrollo de este proyecto es un aporte a la solución de problemas relacionados a la transferencia de información entre diferentes dispositivos electrónicos y a la generación de alternativas de bajo costo para la adquisición y adaptación tecnológica en el área de comunicaciones industriales y automatización industrial Colombiana

Implementación de un algoritmo PID en un controlador Lógico programable bajo una red de comunicación industrial

Este articulo presenta la implementación de un algoritmo PID en un PLC click Koyo integrado a una red de comunicación industrial, bajo el protocolo Modbus RTU, como parte de un modulo didáctico de automatización. El proyecto permite tener herramientas pedagógicas para el estudio en el análisis de respuesta y comportamiento de controladores a través de una interfaz grafica HMI en tiempo real bajo una red de comunicación industrial. El desarrollo de este proyecto es un aporte a la solución de problemas y a la generación de alternativas de bajo costo para la adquisición y adaptación tecnológica en el área de comunicaciones industriales, automatización y control

Catalytic Aspects of Pt/Pd Supported on ZnO Rods for Hydrogen Production in Methanol Steam Reforming

We present a combined experimental and theoretical study for catalytic performance of Pt/Pd supported on ZnO rods for methanol steam reforming reaction (MSR) for hydrogen production. The samples were extensively characterized by Adsorption– Desorption of N2 (BET), electron microscopy in scanning and transmission mode (SEM/TEM), X-ray diffraction (XRD), temperature programed reduction (TPR), and mass spectroscopy (MS). Results, showed typical diffraction peaks corresponding to hexagonal Zincite structure and tetragonal PtZn, PdZn and PtPdZn alloys which were identified by XRD, HRTEM and the last structure by modeling simulation. The crystallographic characterization after catalytic testing indicates that intermetallic PtZn phase on Pt/ZnO sample was more stable in comparison to PdZn on Pd/ZnO catalyst. In addition, Pt stabilize the PdZn structure in the bimetallic catalyst. The catalytic reactivity measured from 200 to 450 °C, indicates that Pt/ZnO-rod sample possess superior catalytic activity from the series as completed on this study. The methanol conversion was tracked by mass spectroscopy concluding minimal changes in outlet signals which suggests samples are chemically stable throughout the complete catalytic reaction. Furthermore, the computer assisted density of states calculations indicate that electron donation from platinum into the zinc oxide support might be the explanation for better catalytic performance