Nanofiltration applications of tough MWNT buckypaper membranes containing biopolymers

© 2017 Elsevier B.V. The ability of biopolymers (bovine serum albumin, lysozyme, chitosan, gellan gum and DNA) to facilitate formation of aqueous dispersions of MWNTs was investigated using a combination of absorption spectrophotometry and optical microscopy. Subsequently, self-supporting carbon nanotube membranes, known as buckypapers (BPs), were prepared by vacuum filtration of the dispersions. Microanalytical data obtained from the BPs confirmed the retention of biopolymers within their structures. Tensile test measurements performed on the BPs showed that incorporation of the biopolymers resulted in significant improvements in mechanical properties, compared to analogous BPs containing MWNTs and the low molecular mass dispersant Triton X-100. For example, MWNT/CHT BPs (CHT=chitosan) exhibited values for tensile strength, ductility, Young's modulus and toughness of 28±2 MPa, 5.3±2.7%, 0.9±0.3 GPa and 1.7±0.3 J g−1, respectively. Each of these values are significantly greater than those obtained for MWNT/Trix BPs, prepared using a low molecular weight dispersant (6±3 MPa, 1.3±0.2%, 0.6±0.3 GPa and 0.10±0.06 J g−1, respectively). This significant improvement in mechanical properties is attributed to the ability of the long biopolymer molecules to act as flexible bridges between the short CNTs. All BPs possessed hydrophilic surfaces, with contact angles ranging from 29±2° to 57±5°. Nitrogen gas porosimetry showed that the BPs have highly porous internal structures, while scanning electron microscopy (SEM) showed their surface morphologies have numerous pore openings. The permeability of the BPs towards water, inorganic salts, and dissolved trace organic contaminants (TrOCs), such as pharmaceuticals, personal care products, and pesticides, was investigated through filtration experiments. Of the twelve TrOCs investigated in this study, nine were rejected by more than 95% by BPs composed of MWNTs and chitosan. The latter BPs also demonstrated good rejection of both NaCl (30–55%) and MgSO4(40–70%)

Infotecnología y gestión de la información en la carrera de economía / Info-technology and information management in Economic major

El artículo describe el proceso de formación y desarrollo de la competencia gestionar información con el empleo de la infotecnología en la carrera de Economía. Luego de identificar las insuficiencias que presentan los estudiantes en su gestión informativa con el uso de la tecnología disponible y el pobre aprovechamiento del potencialpara la aplicación de conocimientos, se modela la formación y desarrollo de la competencia como sistema de relaciones que explican la dinámica e interacción entre los procesos de orientación valorativa, apropiación del conocimiento e instrumental informacional-infotecnológico y la valoración contrastada de su actuación.Todo ello sirvió como base para establecer una estrategia didáctica que contribuye al mejor desempeño del estudiante en el contexto académico, profesional y social. Los resultados de la investigación han sido consecuencia de la aplicación de métodos de investigación científica, los autores han validado mediante un pre-experimento las potencialidades de la estrategia que propicia el desarrollo continuo en la profesión en tanto, cultura de trabajo profesional del economista.AbstractThe paper describes the competency-based education of students of economics in new technologies assisted information management. After identifying students’ difficulties in information management and the shortcomings of the teaching-learning process, the authors designed a model for info-technology assisted information management competency-based training. The model is described as a system of relations explaining the interactive dynamics of the processes of assessing orientation, instrumental appropriation, informational and information technology knowledge in appraising performance.This theoretical framework provides the foundations of a didactic strategy fostering students’ performance at academic, professional and social environment. The findings derive from the application of methods of scientific research. The potentials of the cultural, economic and professional developmental strategy were experimentally tested

Infotecnología y gestión de la información en la carrera de economía / Info-technology and information management in Economic major

El artículo describe el proceso de formación y desarrollo de la competencia gestionar información con el empleo de la infotecnología en la carrera de Economía. Luego de identificar las insuficiencias que presentan los estudiantes en su gestión informativa con el uso de la tecnología disponible y el pobre aprovechamiento del potencialpara la aplicación de conocimientos, se modela la formación y desarrollo de la competencia como sistema de relaciones que explican la dinámica e interacción entre los procesos de orientación valorativa, apropiación del conocimiento e instrumental informacional-infotecnológico y la valoración contrastada de su actuación.Todo ello sirvió como base para establecer una estrategia didáctica que contribuye al mejor desempeño del estudiante en el contexto académico, profesional y social. Los resultados de la investigación han sido consecuencia de la aplicación de métodos de investigación científica, los autores han validado mediante un pre-experimento las potencialidades de la estrategia que propicia el desarrollo continuo en la profesión en tanto, cultura de trabajo profesional del economista.AbstractThe paper describes the competency-based education of students of economics in new technologies assisted information management. After identifying students’ difficulties in information management and the shortcomings of the teaching-learning process, the authors designed a model for info-technology assisted information management competency-based training. The model is described as a system of relations explaining the interactive dynamics of the processes of assessing orientation, instrumental appropriation, informational and information technology knowledge in appraising performance.This theoretical framework provides the foundations of a didactic strategy fostering students’ performance at academic, professional and social environment. The findings derive from the application of methods of scientific research. The potentials of the cultural, economic and professional developmental strategy were experimentally tested

La gestión de información y la infotecnología en la formación del profesional de las Ciencias Económicas y Empresariales

Se analizó la gestión de información y su relación con la infotecnología para la formación profesional del estudiante de la carrera Licenciatura en Economía. Se evidenció la necesidad de desarrollar sistemáticamente la habilidad gestión de información durante el proceso formativo del alumno. Se elaboró una estrategia basada en la realización de actividades con el uso de herramientas infotecnológicas que fomente el conocimiento de mecanismos para: la navegación, la búsqueda, la revisión, el procesamiento y la socialización de la información en formato digital

Influence of lip closure on alveolar cleft width in patients with cleft lip and palate

<p>Abstract</p> <p>Background</p> <p>The influence of surgery on growth and stability after treatment in patients with cleft lip and palate are topics still under discussion. The aim of the present study was to investigate the influence of early lip closure on the width of the alveolar cleft using dental casts.</p> <p>Methods</p> <p>A total of 44 clefts were investigated using plaster casts, 30 unilateral and 7 bilateral clefts. All infants received a passive molding plate a few days after birth. The age at the time of closure of the lip was 2.1 month in average (range 1-6 months). Plaster casts were obtained at the following stages: shortly after birth, prior to lip closure, prior to soft palate closure. We determined the width of the alveolar cleft before lip closure and prior to soft palate closure measuring the alveolar cleft width from the most lateral point of the premaxilla/anterior segment to the most medial point of the smaller segment.</p> <p>Results</p> <p>After lip closure 15 clefts presented with a width of 0 mm, meaning that the mucosa of the segments was almost touching one another. 19 clefts showed a width of up to 2 mm and 10 clefts were still over 2 mm wide. This means a reduction of 0% in 5 clefts, of 1-50% in 6 clefts, of 51-99% in 19 clefts, and of 100% in 14 clefts.</p> <p>Conclusions</p> <p>Early lip closure reduces alveolar cleft width. In most cases our aim of a remaining cleft width of 2 mm or less can be achieved. These are promising conditions for primary alveolar bone grafting to restore the dental bony arch.</p

A tin-free route to trans -Diels-Alder motifs by visible light photoredox catalysis

A tin-free trans-Diels-Alder paradigm for the stereoselective synthesis of trans-fused polycyclic systems was developed through the photocatalytic reductive dehalogenation of α-haloketones promoted by visible light. Good to excellent diastereoselectivities were observed in the stereoselective construction of trans-fused octalone derivatives under mild reaction conditions. © 2015 American Chemical Society1661sciescopu