Efficient continuous removal of nitrates from water with cationic cellulose nanopaper membranes

Nitrates constitute a severe problem for the quality of potable water. The removal of nitrates from water can be performed utilizing continuously operating cellulose nanopaper ion-exchangers, which so far are unfortunately of only moderate efficiency. Here we demonstrate cationic cellulose nanopapers comprising cellulose nanofibrils carrying a high amount of ammonium groups (1.6 g mmol−1, i.e. 0.62 mmol g−1), which are anticipated to enable efficient removal of nitrate ions from aqueous solutions. Thin nanopapers were shown to have high adsorption capacities. Therefore we prepared low grammage nanopapers using a papermaking process from cellulose nanofibrils prepared from paper mill sludge. The performance of these cationic nanopapers was characterized by their permeance, with these new cationic nanopapers having a permeance of more than 100 L m−2 h−1 MPa−1, which is far greater than the permeance of conventional nanopapers. Furthermore, nitrate ions were successfully removed from water by capturing them through adsorption onto the cationic nanopaper by primarily an ion-exchange mechanism. These cationic nanopapers possessed adsorption capacities of almost 300 mg g−1, which is superior to commonly used nanopaper ion-exchangers and batch-wise applied adsorbents. Utilization of an industrial side-stream in combination with very good membrane performance demonstrates the use of resource efficient technologies in an important sector

Polystyrene-grafted Carbon Fibers: Surface Properties and Adhesion to Polystyrene

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.It is highly desirable to improve attractive interactions between carbon fibers and unreactive thermoplastic matrices to the possible maximum. This could be achieved by a simple grafting process to create a covalently bonded interface or interlayer, which should result in cohesive interactions between the polymer-grafted fibers and the same matrix material, leading to a better adhesion strength in the obtained composite material. Here, we are describing the grafting of styrene onto unmodified and unsized carbon fibers via free-radical bulk polymerization in the presence of fibers. After grafting, the surface properties of the carbon fiber approach those of pure polystyrene which was proven by contact angle and zeta (ζ) potential measurements. As indicated by the water contact angle, the carbon fiber surface becomes more hydrophobic. Scanning electron microscopy (SEM) provides evidence of grafted polymer. This simple procedure results in a continuous polystyrene coating. The fiber diameter increases significantly after polymer grafting. The adhesion and fracture behavior between the original and polystyrene-grafted carbon fibers to a polystyrene (VESTYRON®) matrix was characterized using the single-fiber pull-out test. There is a considerable increase in the measurable adhesion, i.e., the interfacial shear strength IFSS, by almost 300% between the grafted fibers and polystyrene as compared to untreated original fibers. Two planes of interfacial failure could be distinguished; first in the fiber coating interface leading to lower interfacial shear strength and second in the PS-matrix-PS-coating interphase resulting in a higher interfacial shear strength. In addition to the improved adhesion, there are also clear differences in the pull-out behavior between the nongrafted and grafted fibers. After the initial debonding process corresponding to the maximal pull-out force is completed, the pull-out force is increasing again

Structural Batteries for Aeronautic Applications—State of the Art, Research Gaps and Technology Development Needs

Radical innovations for all aircraft systems and subsystems are needed for realizing future carbon-neutral aircraft, with hybrid-electric aircraft due to be delivered after 2035, initially in the regional aircraft segment of the industry. Electrical energy storage is one key element here, demanding safe, energy-dense, lightweight technologies. Combining load-bearing with energy storage capabilities to create multifunctional structural batteries is a promising way to minimize the detrimental impact of battery weight on the aircraft. However, despite the various concepts developed in recent years, their viability has been demonstrated mostly at the material or coupon level, leaving many open questions concerning their applicability to structural elements of a relevant size for implementation into the airframe. This review aims at providing an overview of recent approaches for structural batteries, assessing their multifunctional performance, and identifying gaps in technology development toward their introduction for commercial aeronautic applications. The main areas where substantial progress needs to be achieved are materials, for better energy storage capabilities; structural integration and aircraft design, for optimizing the mechanical-electrical performance and lifetime; aeronautically compatible manufacturing techniques; and the testing and monitoring of multifunctional structures. Finally, structural batteries will introduce novel aspects to the certification framework

Resolución de problemas en Área y Volumen de la Esfera, aplicando Método de Polya, décimo grado, turno matutino, Instituto Nacional San Ramón, Matagalpa, segundo semestre 2017

El abordaje de la Geometría de Sólidos requiere de la implementación de Métodos para la resolución de problemas en Área y Volumen de temas como el de la Esfera, los cuales permitan una mejor comprensión en el estudiante y a su vez estos puedan desarrollar el análisis crítico. Esta investigación aborda la problemática con el propósito de analizar la aplicación del método de Polya en la resolución de problemas en Área y Volumen de la Esfera, décimo grado, turno matutino, Instituto Nacional San Ramón, Matagalpa, segundo semestre 2017. Esta investigación, adquiere relevancia por tener gran influencia en el desarrollo de los estudiantes, sobre todo en las capacidades relacionadas con la comunicación y relación con el entorno. Los problemas equipan a los estudiantes con un potente conjunto de herramientas las cuales aportan a su desarrollo intelectual y su capacidad de análisis. Con esta investigación se verificó que los problemas que se están resolviendo, relacionados al Área y Volumen de la Esfera con estudiantes de décimo grado son problemas de rutina. Se identificó que los problemas se realizan de forma inmediata siguiendo una serie de pasos o algoritmos que permiten llegar a una solución de forma más rápida. En la resolución de problemas el docente no aplica el Método de Polya, esto se debe a la falta de conocimiento sobre cómo se realiza su proceso de aplicación. Por tal razón fue necesario realizar una Propuesta Metodológica de Resolución de problemas en Área y Volumen de la Esfera aplicando el Método de Poly

Resolución de problemas en Área y Volumen de la Esfera, aplicando Método de Polya, décimo grado, turno matutino, Instituto Nacional San Ramón, Matagalpa, segundo semestre 2017

El abordaje de la Geometría de Sólidos requiere de la implementación de Métodos para la resolución de problemas en Área y Volumen de temas como el de la Esfera, los cuales permitan una mejor comprensión en el estudiante y a su vez estos puedan desarrollar el análisis crítico. Esta investigación aborda la problemática con el propósito de analizar la aplicación del método de Polya en la resolución de problemas en Área y Volumen de la Esfera, décimo grado, turno matutino, Instituto Nacional San Ramón, Matagalpa, segundo semestre 2017. Esta investigación, adquiere relevancia por tener gran influencia en el desarrollo de los estudiantes, sobre todo en las capacidades relacionadas con la comunicación y relación con el entorno. Los problemas equipan a los estudiantes con un potente conjunto de herramientas las cuales aportan a su desarrollo intelectual y su capacidad de análisis. Con esta investigación se verificó que los problemas que se están resolviendo, relacionados al Área y Volumen de la Esfera con estudiantes de décimo grado son problemas de rutina. Se identificó que los problemas se realizan de forma inmediata siguiendo una serie de pasos o algoritmos que permiten llegar a una solución de forma más rápida. En la resolución de problemas el docente no aplica el Método de Polya, esto se debe a la falta de conocimiento sobre cómo se realiza su proceso de aplicación. Por tal razón fue necesario realizar una Propuesta Metodológica de Resolución de problemas en Área y Volumen de la Esfera aplicando el Método de Poly

Effect of Plasma-Treatment of Interleaved Thermoplastic Films on Delamination in Interlayer Fibre Hybrid Composite Laminates

Safe, light, and high-performance engineering structures may be generated by adopting composite materials with stable damage process (i.e., without catastrophic delamination). Interlayer hybrid composites may fail stably by suppressing catastrophic interlayer delamination. This paper provides a detailed analysis of delamination occurring in poly(acrylonitrile-butadiene-styrene) (ABS) or polystyrene (PS) film interleaved carbon-glass/epoxy hybrid composites. The ABS films toughened the interfaces of the hybrid laminates, generating materials with higher mode II interlaminar fracture toughness (GIIC), delamination stress (σdel), and eliminating the stress drops observed in the reference baseline material, i.e., without interleaf films, during tensile tests. Furthermore, stable behaviour was achieved by treating the ABS films in oxygen plasma. The mechanical performance (GIIC and σdel) of hybrid composites containing PS films, were initially reduced but increased after oxygen plasma treatment. The plasma treatment introduced O-C=O and O-C-O-O functional groups on the PS surfaces, enabling better epoxy/PS interactions. Microscopy analysis provided evidence of the toughening mechanisms, i.e., crack deflection, leading plasma-treated PS to stabilise delamination

Importancia de la Educación Física en el desarrollo y fortalecimiento del sistema óseo en estudiantes de 6to grado “A” colegio público Rubén Darío, municipio de Matagalpa, segundo semestre del año académico 2017

El presente Seminario de Graduación tiene como propósito fundamental hacer una valoración sobre la Importancia de la Educación Física en el desarrollo y fortalecimiento del sistema óseo en estudiantes de sexto grado “A” colegio público Rubén Darío municipio de Matagalpa, segundo semestre del año académico 2017. Dicho estudio se realizó como una necesidad de indagar acerca del impacto que tiene esta disciplina dentro del ámbito educativo. Este estudio se considera de gran trascendencia dentro de la disciplina de educación física, porque no solamente contiene información relacionada con los beneficios del desarrollo y fortalecimiento del sistema óseo muscular, sino que también mejora el desempeño del ser humano para tener una mejor calidad de vida. Esta ha sido la motivación de investigar la incidencia de la Importancia de la educación física en el desarrollo y fortalecimiento del sistema óseo en estudiantes de sexto grado “A” colegio público Rubén Darío municipio de Matagalpa del segundo semestre del año académico 2017, tomando como puntos esenciales los beneficios y su importancia cómo estrategia muy productiva en los niños. Cabe señalar que de acuerdo a los propósitos planteados en este estudio, están vinculados a una salud completa e integral, porque su importancia es determinante en el desarrollo y fortalecimiento del sistema óseo en los estudiante

Property and Shape Modulation of Carbon Fibers Using Lasers

An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cotton-bud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes