Thermal and mechanical properties of chitosan nanocomposites with cellulose modified in ionic liquids

In this paper, ionic liquid treatment was applied to produce nanometric cellulose particles of two polymorphic forms. A complex characterization of nanofillers including wide-angle X-ray scattering, Fourier transform infrared spectroscopy, and particle size determination was performed. The evaluated ionic liquid treatment was effective in terms of nanocrystalline cellulose production, leaving chemical and supermolecular structure of the materials intact. However, nanocrystalline cellulose II was found to be more prone to ionic liquid hydrolysis leading to formation larger amount of small particles. Each nanocrystalline cellulose was subsequently mixed with a solution of chitosan, so that composite films containing 1, 3, and 5% mass/mass of nanometric filler were obtained. Reference samples of chitosan and chitosan with micrometric celluloses were also solvent casted. Thermal, mechanical, and morphological properties of films were tested and correlated with properties of filler used. The results of both, tensile tests and thermogravimetric analysis showed a significant discrepancy between composites filled with nanocrystalline cellulose I and nanocrystalline cellulose II

Approaches in biotechnological applications of natural polymers

Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them are reviewed in this article.. }To the Conselho Nacional de Desenvolvimento Cientfíico e Tecnológico (CNPq) for fellowships (LCBBC and MGCC) and the Coordenação de Aperfeiçoamento de Pessoal de Nvíel Superior (CAPES) (PBSA). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and COMPETE 2020 (POCI-01-0145-FEDER-006684) (JAT)

Caracterização morfológica de nanocristais de celulose por microscopia de força atômica

RESUMO O isolamento de nanocristais de celulose (CNCs) de fibras vegetais é uma alternativa promissora para sua aplicação como reforço em matrizes poliméricas. A caracterização dos CNCs é fundamental para a confiabilidade da técnica, além de determinar as aplicações possíveis a partir de cada tipo de fibra. A partir da técnica de microscopia de força atômica, um estudo da morfologia e distribuição dos CNCs de semente de manga, vagem de algaroba, pseudocaule da bananeira e fibra do mesocarpo de dendê foi realizado neste trabalho. Os CNCs foram obtidos via reação hidrolítica com ácido sulfúrico em concentrações que variaram de acordo com a fonte da fibra. Os resultados obtidos revelaram dimensões variando de 300 a 500 nm em comprimento e 4 a 16 nm em diâmetro. A apresentação morfológica em forma de agulha demonstrou que o isolamento das fibras de celulose em CNCs foi efetiva. A razão de aspecto associada à formação cilíndrica em agulha dos CNCs isolados evidenciou o alto potencial das fontes de dendê e de vagem de algaroba para o reforço de bionanocompósitos

A procedure for urban route travel time forecast based on advanced traffic data: Case study of Rome

In this paper, authors report a procedure to forecast the route travel time, based on different advanced traffic data, both historical and current. The procedure is articulated in two main steps: the first consists in apportioning current route travel time among the links based on historical Floating Car Data; in second step, the obtained link travel times are combined with the current loop detectors data through the measurement data fusion technique; moreover, the Extended Kalman Filter (EKF) correction is applied to a second order traffic model, in order to forecast the link speeds and consequently link and route travel times. Real applications of the proposed procedure concerning both a signalized route of Lungotevere and 6.5 kilometers urban freeway with 14 on/off-ramps in Rome are reported. The results of the forecasted route travel time show a good accuracy until the detected data used to correct the estimation are coherent and the input data, such as flows on ramps, are reliable. The results of the link speeds in terms of RMSE and RME with respect to the data detected by the loop sensors seem to be accurate, however further development will deal with the comparison to the other existing methods. Finally, the results underline, as it is well known, the need of real and reliable data in order to provide a good forecast

Bus dispatching irregularity and travel time dispersion

Service reliability is one of the most important determinants for shifting people to public transport. In low-frequency services, the reliability is considered in terms of punctuality, which becomes significant also from the standpoint of operators, given that punctuality indicators are generally included in business models. As a support for further improvement in bus punctuality in the urban area of Rome, analyses were carried out using automatic vehicle location (AVL) data of a bus line with services mixed with other traffic components and therefore subject to high degrees of travel time variability. The analyses allowed the systematic components of bus dispatching irregularity to be revealed and to investigate to what extent these components are influenced by road congestion, and hence by delayed arrival times at terminals

Analysing urban traflc volumes and mapping noise emissions in Rome (Italy) in the context of containment measures for the COVID-19 disease

This study presents the result of a traffic simulation analysis based on Floating Car Data and a noise emission assessment to show the impact of mobility restriction for COVID-19 containment on urban vehicular traffic and road noise pollution on the road network of Rome, Italy. The adoption of strong and severe measures to contain the spreading of Coronavirus during March-April 2020 generated a significant reduction in private vehicle trips in the city of Rome (-64.6% during the lockdown). Traffic volumes, obtained through a simulation approach, were used as input parameters for a noise emission assessment conducted using the CNOSSOS-EU method, and an overall noise emissions reduction on the entire road network was found, even if its extent varied between road types