Cellulose - Chitosan Nanocomposites - Evaluation of Physical, Mechanical and Biological Properties

This research describes the preparation of membranes with chitosan (CS) as the polymeric matrix and cellulose nanocrystals (CNC) as reinforcement. The aim was to evaluate their physical, mechanical and biological properties, and to determine their potential for biomedical use. Membranes were prepared via casting CNC suspensions in CS solution, at CNC concentrations of 0.5%, 1.0% and 2.0% (w/w) with pure chitosan as a reference. Analysis of membrane properties was performed using several techniques, such as ATR – FTIR, SEM, swelling test, maximum water absorption, dynamical mechanical analysis and in vivo (Winstar rats) biocompatibility and biodegradability assays for biological evaluation. Experimental results established that CNC reduced swelling rates and increased the maximum water absorption when CNC concentration was higher. Therefore, the presence of CNC in the matrix reduced Young’s modulus by approximately 50% in comparison with pure chitosan. All formulations demonstrated biocompatibility and biodegradability values ranged between 4% and 21% in the 30 days after implantation. Based on these results, these membranes may be of use for biomedical applications

Impact of process variables on the micromeritic and physicochemical properties of spray-dried porous microparticles, part I: introduction of a new morphology classification system

YesObjectives This work investigated the impact of spray drying variables such as feedconcentration, solvent composition and the drying mode, on the micromeriticproperties of chlorothiazide sodium (CTZNa) and chlorothiazide potassium(CTZK).Methods Microparticles were prepared by spray drying and characterised usingthermal analysis, helium pycnometry, laser diffraction, specific surface area analysisand scanning electron microscopy.Key findings Microparticles produced under different process conditions pre-sented several types of morphology.To systematise the description of morphology ofmicroparticles, a novel morphology classification system was introduced. The shapeof the microparticles was described as spherical (1) or irregular (2) and the surfacewas classified as smooth (A) or crumpled (B). Three classes of morphology of micro-particles were discerned visually: class I, non-porous; classes II and III, comprisingdiffering types of porosity characteristics. The interior was categorised as solid/continuous (a), hollow (b), unknown (g) and hollow with microparticulate content(d). Nanoporous microparticles of CTZNa and CTZK, produced without recircula-tion of the drying gas, had the largest specific surface area of 72.3 and 90.2 m2/g,respectively, and presented morphology of class 1BIIIa.Conclusions Alteration of spray drying process variables, particularly solvent com-position and feed concentration can have a significant effect on the morphology ofspray dried microparticulate products. Morphology of spray dried particles may beusefully described using the morphology classification system.The Irish Research Council for Science and Engineering Technology (IRCSET), the Solid State Pharmaceutical Cluster (SSPC), supported by Science Foundation Ireland under grant number [07/SRC/B1158] and the Irish Drug Delivery Research Network, a Strategic Research Cluster grant (07/SRC/B1154) under the National Development Plan co-funded by EU Structural Funds and Science Foundation Ireland

Estudio teórico y experimental del sistema 9 Be + 51 V y sistemas similares

En este trabajo de tesis se presenta el estudio sistemático de los sistemas 7Li + 51V, 9Be + 51V y 8B + 58Ni. Para los sistemas ( 7Li, 9 Be) + 51V se midieron las secciones eficaces de fusión a energías cercanas a la barrera Coulombiana (EB,lab=11.75 y 16.16 MeV, respectivamente) empleando la técnica de rayos γ. El experimento para medir la fusión se llevó a cabo en el Laboratorio del Acelerador Tan- dem, del Instituto Nacional de Investigaciones Nucleares (ININ), siendo éstas las primeras mediciones realizadas para estos proyectiles a las energías consideradas. De forma simultánea, se hizo el análisis de los posibles núcleos residuales usando los códigos computacionales de fusión-evaporación PACE2, LILITA y CASCADE. Los resultados obtenidos fueron comparados con los datos experimentales me- didos. De forma preliminar, para el sistema 7Li + 51V, se hicieron cálculos usando la teoría de canales acoplados de reacción para estimar la contribución de la sección eficaz de transferencia de un protón a la producción del núcleo residual 52Cr. Para el sistema 8B + 58Ni, se hizo un análisis teórico de canales acoplados con el continuo discretizado y canales acoplados de reacción para estudiar los procesos de rompimiento y de transfe- rencia de un protón, 58Ni(8B,7Be)59Cu, a energías alrededor de la barrera Coulombiana (EB,lab=22.95 MeV). Para calcular las secciones eficaces correspondientes se usó un potencial de Modelo Óptico se- mimicroscópico, el cual combina un potencial real de doble convolución, un potencial de polarización y un potencial imaginario tipo Woods-Saxon. A partir de la comparación de nuestros cálculos con datos experimentales se determinaron los factores espectroscópicos Sexpt y astrofísicos S17(0) del protón en la interacción 8B → 7Be+p

El pino mexicano, de la biología a la estética

México es el país con más especies de pinos en el mundo. De más de cien especies que se tiene registro, México cuenta con alrededor de 43. “Los pinos no son aquellos que se usan en navidad, esos son coníferas, los pinos son los que producen el fruto que llamamos “piñas”. Así les dicen todos, porque se parecen, pero no lo son”, comenta Fernando López Dellamary. Este investigador de la Universidad de Guadalajara ahonda en esta charla en lo que representa que México ocupe el primer lugar en diversidad de especies del género pinus y la variedad climática y topográfica que produce tener espacios con tanta diversidad, además de advertir lo que pudiera suceder ante la amenaza de la deforestación por causa del cambio de uso de suelo. Fernando López Dellamary es ingeniero químico por la UNAM, tiene una maestría en química orgánica por el ITESM y estudió el doctorado en el área de Recursos Forestales, especializado en química y ciencia de polímeros y fibras en la Universidad de Washington. Es miembro del Sistema Nacional de Investigadores, pertenece a la American Chemical Society y la International Society of Chemical Ecology.ITESO, A.C

Cu2O/TiO2 Nanorod Heterojunctions: Synthesis, Characterization and Applications as Solar Cells on the Nanoscale

Novel solar cells are being synthesized from sustainable, non-toxic, and economic materials. All metal oxide semiconductors are one such class of these materials. Synthesis of different combinations of p and n type MO semiconductors heterojunctions as well as high throughput characterization is crucial to improve their applications in fields such as solar cells. A Cu2O/TiO2 Nanorods heterojunction is synthesized on a fluorine doped tin oxide substrate. The TiO2 Nanorods are synthesized via a two-step, solvothermal method. The Cu2O is deposited conformally on the TiO2 NRs via a physical vapor deposition method known as RF magnetron sputtering, with thicknesses of 100, 50 and 25 nm. Characterization methods are used to first determine that the correct materials were synthesized and deposited. Scanning electron microscopy demonstrated that nanorods were made of length, 750 nm, and width, 45 nm. Optical measurements were taken, including: absorbance, transmittance, and reflectance; trends followed the optical data as the thickness of the p-type material increased. From the absorbance data, the bandgap of the materials could be calculated from the generated Tauc plot. The bandgap of TiO2 was calculated to be 3.0 eV which agreed with literature values. The bandgap of Cu2O was calculated to be 2.76 eV which is not in agreement with literature values. X-ray diffraction demonstrated that TiO2 rutile phase was grown, with diffraction angles at: 36.45, 62.747 and 69.766 with their lattice planes being (011), (002) and (112) respectively. Raman spectroscopy demonstrated TiO2 in the rutile phase with Raman shifts at both 447 cm-1 (Eg) and 609 cm-1(A1g). There is a minor peak at 522 cm-1 (T2g) which correlates to Cu2O. Macro-electrical measurements were taken to plot a current vs voltage curve (IV curve), under dark and light conditions. From the macro-electrical measurements Isc, Voc and η (photoconversion efficiency) were calculated: 2.38 E-09 A, -0.18 V, 7.25E-07 respectively (under light, 1 sun equivalent). Atomic force microscopy (AFM) was used to attain topographical images, force/deflection curves, IV curves/maps, and surface potential maps. Conductive-AFM (c-AFM) and Kelvin Probe Force Microscopy (KPFM) were the specific AFM techniques used. From the KPFM measurements it was possible to measure the work functions of TiO2 NRs and Cu2O/TiO2 NRs by using highly oriented pyrolyzed graphite as a reference. The work function for TiO2 NRs was: 4.24 eV and 4.14 eV under dark and light conditions respectively. The work function of the 100 nm Cu2O/TiO2 NRs heterojunction was 4.44 eV and 4.35 eV under dark and light conditions respectively. The apparent work functions that were calculated via this KPFM method were not in agreement with literature values of the respective materials. This thesis has proved that Cu2O/TiO2 Nanorod Heterojunctions can be synthesized using previously known solvothermal synthetic methods. Furthermore these Cu2O/TiO2 Nanorod Heterojunctions have an increase in current under illumination. This current response under illumination has been studied on the nanoscale, using KPFM and C-AFM, as well as on the macroscale. Further investigations on the nanoscale are to be done, which can shed light on how and why these all metal oxide nanorod heterojunctions are functioning as solar cells.

Mejora de cultivo de Arthrospira maxima en biorreactores utilizando diferentes medios de cultivo

Este proyecto tuvo como objetivos documentar el crecimiento de Spirulina maxima en biorreactores (los cuales forman parte de un módulo diseñado y construido) para mejorar su manera de cosecha y formular medios de cultivo diferentes para evaluar con cuál y a qué concentración crece mejor

Automatización en el cultivo de Arthrospira maxima en fotobiorreactores en Departamento de Ecología del Centro Universitario de Ciencias Biológicas y Agropecuarias de la Universidad de Guadalajara, Guadalajara

En este proyecto se busca automatizar el control y toma de valores fisicoquímicos, mediante sensores, Arduino y una Raspberry Pi 3B, en el cultivo de Arthrospira maxima en el Centro Universitario de Ciencias Biológicas y Agropecuarias (CUCBA) de la Universidad de Guadalajara, en un fotobiorreactor de 1100 litros, además de permitir continuar con la instalación de nuevos sensores en el control de nuevas variables en próximos cursos. Se buscó también modificar el sistema de aireación y turbulencia en el cultivo para dar turbulencia sin aireación tubería directa, mediante un airlift diseñado para este PAP. Se instaló el sistema completo sin funcionar aún con Arthrospira maxima, pero probando que funcionaba con agua para luego hacerse funcionar con Spirulina. El airlift se probó ser funcional.ITESO, A.C

Tiempo en el espacio :las señas temporales de la lengua de señas mexicana

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