59 research outputs found
Estímulo à participação social em conselhos de saúde por meio de estudantes de medicina
O projeto “Fortalecimento da Gestão e Estímulo à Participação Social em Conselhos Regionais de Saúde do Distrito Federal por meio de Estudantes de Medicina e de uma Parceria Estratégica com Profissionais do Programa Família Saudável” foi desenvolvido em junho-dezembro de 2005. As etapas do projeto foram: Diagnóstico da área Areal em Taguatinga-DF e Planejamento Estratégico. O objetivo foi qualificar e ampliar o grau de participação dos conselheiros, tornando mais efetiva a atuação dos Conselhos de Saúde. Diversas metodologias foram utilizadas nas etapas do projeto, sendo que no momento do Diagnóstico da área foram aplicadas a Estimativa Rápida Participativa, a Análise dos dados da Sala de Situação do Centro de Saúde número 05 de Taguatinga e Satisfação do Usuário, avaliada por meio de questionários. A etapa do Planejamento Estratégico resultou da análise dos dados obtidos pelos instrumentos da etapa anterior, sendo realizada a detecção dos principais problemas e proposição de ações para a resolução destes. Os resultados encontrados foram: contraste sócio econômico e cultural, deficiente atenção primária à saúde, educação precária, pavimentação e saneamento básico inadequados. O projeto proporcionou aos estudantes de medicina a inserção na realidade do desafio do controle social em políticas públicas de saúde
Enhancing Self-Assembly in Cellulose Nanocrystal Suspensions Using High-Permittivity Solvents
Helical liquid crystal self-assembly in suspensions of cellulose nanocrystals (CNCs), bioderived nanorods exhibiting excellent mechanical and optical properties, opens attractive routes to sustainable production of advanced functional materials. For convenience, in most studies until now, the CNCs were suspended in water, leaving a knowledge gap concerning the influence of the solvent. Using a novel approach for aggregation-free solvent exchange in CNC suspensions, here we show that protic solvents with a high dielectric permittivity εr significantly speed up self-assembly (from days to hours) at high CNC mass fraction and reduce the concentration dependence of the helix period (variation reducing from more than 30 μm to less than 1 μm). Moreover, our computer simulations indicate that the degree of order at constant CNC content increases with increasing εr, leading to a shorter pitch and a reduced threshold for liquid crystallinity. In low-εr solvents, the onset of long-range orientational order is coupled to kinetic arrest, preventing the formation of a helical superstructure. Our results show that the choice of solvent is a powerful parameter for tuning the behavior of CNC suspensions, enhancing our ability to control the self-assembly and thereby harvesting valuable novel cellulose-based materials
Equilibrium Liquid Crystal Phase Diagrams and Detection of Kinetic Arrest in Cellulose Nanocrystal Suspensions
The cholesteric liquid crystal self-assembly of water-suspended cellulose nanocrystal
(CNC) into a helical arrangement was observed already more than 20 years ago, and
the phenomenon was used to produce iridescent solid films by evaporating the solvent
or via sol–gel processing. Yet, it remains challenging to produce optically uniform films
and to control the pitch reproducibly, reflecting the complexity of the three-stage drying
process that is followed in preparing the films. An equilibrium liquid crystal phase formation
stage is followed by a non-equilibrium kinetic arrest, which in turn is followed by
structural collapse as the remaining solvent is evaporated. Here, we focus on the first of
these stages, combining a set of systematic rheology and polarizing optics experiments
with computer simulations to establish a detailed phase diagram of aqueous CNC suspensions
with two different values of the surface charge, up to the concentration where
kinetic arrest sets in. We also study the effect of varying ionic strength of the solvent.
Within the cholesteric phase regime, we measure the equilibrium helical pitch as a function
of the same parameters. We report a hitherto unnoticed change in character of the
isotropic–cholesteric transition at increasing ionic strength, with a continuous weakening
of the first-order character up to the point where phase coexistence is difficult to detect
macroscopically due to substantial critical fluctuations
Efecto de paclobutrazol y Glomus intraradices en el cultivo de Lilium cv. Armandale y Tresor
Los reguladores de crecimiento vegetal se han utilizado para mejorar el aspecto visual de las ornamentales, y la aplicación de micorrizas para facilitar la absorción de fósforo. En esta investigación, se evaluó el efecto de tres concentraciones de paclobutrazol y un inóculo con esporas de Glomus intraradices en el crecimiento, floración y distribución de biomasa de Lilium cv. Armandale y Tresor, fertirrigados con solución nutritiva completa o deficiente de fósforo. Cuarenta y cinco bulbos de cada cultivar fueron sumergidos en soluciones con 0, 50 o 200 mg L-1 de paclobutrazol y plantados en macetas con 2,5 L de tezontle, a 15 bulbos se les espolvoreó 1 g del inóculo antes de su plantación. Los resultados mostraron que Lilium ‘Armandale’ fue más alto (59,13 cm) que ‘Tresor’ (47,80 cm). En ambos cultivares, paclobutrazol redujo la altura y los tipos de riego no afectaron esta variable. El número de hojas (89), diámetro (17,90 mm) y longitud (47,49 mm) de botones florales fueron similares en ‘Armandale’ y ‘Tresor’. El número y biomasa fresca de los botones florales fueron 1,3 y 2,5 veces mayores en ‘Tresor’ cuyos tallos florales fueron visualmente más llamativos. El fertirriego con solución nutritiva deficiente de fósforo en bulbos inoculados incrementó la biomasa seca de raíces, pero no la de tallos y hojas, es decir, el efecto positivo del inóculo ocurrió en el sitio de interacción hongo-planta.
Controlling the Photonic Properties of Cholesteric Cellulose Nanocrystal Films with Magnets
The self-assembly of cellulose nanocrystals is a powerful method for the fabrication of biosourced photonic films with a chiral optical response. While various techniques have been exploited to tune the optical properties of such systems, the presence of external fields has yet to be reported to significantly modify their optical properties. In this work, by using small commercial magnets (≈ 0.5-1.2 T) the orientation of the cholesteric domains is enabled to tune in suspension as they assemble into films. A detailed analysis of these films shows an unprecedented control of their angular response. This simple and yet powerful technique unlocks new possibilities in designing the visual appearance of such iridescent films, ranging from metallic to pixelated or matt textures, paving the way for the development of truly sustainable photonic pigments in coatings, cosmetics, and security labeling.This work was supported by a BBSRC David Phillips fellowship [BB/K014617/1], the EPSRC [1525292] and the European Research Council [ERC-2014-STG H2020 639088]
Fractionation of cellulose nanocrystals : enhancing liquid crystal ordering without promoting gelation
Colloids of electrically charged nanorods can spontaneously develop a fluid yet ordered liquid crystal phase, but this ordering competes with a tendency to form a gel of percolating rods. The threshold for ordering is reduced by increasing the rod aspect ratio, but the percolation threshold is also reduced with this change; hence, prediction of the outcome is nontrivial. Here, we show that by establishing the phase behavior of suspensions of cellulose nanocrystals (CNCs) fractionated according to length, an increased aspect ratio can strongly favor liquid crystallinity without necessarily influencing gelation. Gelation is instead triggered by increasing the counterion concentration until the CNCs lose colloidal stability, triggering linear aggregation, which promotes percolation regardless of the original rod aspect ratio. Our results shine new light on the competition between liquid crystal formation and gelation in nanoparticle suspensions and provide a path for enhanced control of CNC self-organization for applications in photonic crystal paper or advanced composites
Methyl cellulose/cellulose nanocrystal nanocomposite fibers with high ductility
Methylcellulose/cellulose nanocrystal (MC/CNC) nanocomposite fibers showing high ductility and high modulus of toughness were prepared by a simple aqueous wet-spinning from corresponding nanocomposite hydrogels into ethanol coagulation bath followed by drying. The hydrogel MC aq. concentration was maintained at 1 wt-% while the CNC aq. loading was systematically varied in the range 0 – 3 wt-%. This approach resulted in MC/CNC fiber compositions from 25/75 wt-%/wt-% to 95/5 wt-%/wt-%. The optimal mechanical properties were achieved with the MC/CNC composition of 80/20 wt-%/wt-% allowing high strain (36.1 %) and modulus of toughness (48.3 MJ/m3), still keeping a high strength (190 MPa). Further, we demonstrate that the continuous spinning of MC/CNC fibers is potentially possible. The results indicate possibilities to spin MC-based highly ductile composite fibers from environmentally benign aqueous solvents.Peer reviewe
Dynamically Controlled Iridescence of Cholesteric Cellulose Nanocrystal Suspensions Using Electric Fields
Cellulose nanocrystal suspensions in apolar solvent spontaneously form iridescent liquid crystalline phases but the control of their macroscopic order is usually poor. The use of electric fields can provide control on the cholesteric orientation and its periodicity, allowing macroscopic sample homogeneity and dynamical tuning of their iridescent hues, and is demonstrated here.The authors acknowledge funding by the French National Research Agency under grant agreement ANR-08-NANO-P235-36 and B.F-P. acknowledges the Travel Grant COST-STSM-FP1205-30247
HE-LHC: The High-Energy Large Hadron Collider: Future Circular Collider Conceptual Design Report Volume 4
In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre-of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries
FCC Physics Opportunities: Future Circular Collider Conceptual Design Report Volume 1
We review the physics opportunities of the Future Circular Collider, covering its e+e-, pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the synergy and complementarity of the different colliders, which will contribute to a uniquely coherent and ambitious research programme, providing an unmatchable combination of precision and sensitivity to new physics
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