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)

Coordinated observations of migrating tides by multiple meteor radars in the equatorial mesosphere and lower thermosphere

We present the migrating tidal winds decomposed jointly from multiple meteor radars in four longitudinal sectors situated in the equatorial mesosphere and lower thermosphere (MLT). The radars are located in Cariri, Brazil (7.4° S, 36.5° W), Kototabang, Indonesia (0.2° S, 100.3° E), Ascension Island, United Kingdom (7.9° S, 14.4° W), and Darwin, Australia (12.3° S, 130.8° E). Harmonic analysis was used to obtain amplitudes and phases for diurnal and semidiurnal solar migrating tides between 82 and 98 km altitude during the period 2005 to 2008. To verify the reliability of the tidal components calculated by the four meteor radar wind measurements, we also present a similar analysis for the Whole Atmosphere Community Climate Model (WACCM) winds, which suggests that the migrating tides are well observed by the four different radars. The tides include the important tidal components of diurnal westward-propagating zonal wavenumber 1 (DW1) and semidiurnal westward-propagating zonal wavenumber 2 (SW2). In addition, the results based on observations were compared with the Climatological Tidal Model of the Thermosphere (CTMT). In general, in terms of climatic features, our results for the major components of migrating tides are qualitatively consistent with the CTMT models derived from satellite data. In addition, the tidal amplitudes are unusually stronger in January-February 2006. This result is probably because tides were enhanced by the 2006 northern hemisphere stratospheric sudden warming (NH-SSW) event