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)

Facilitated UASB granule formation using organic-inorganic hybrid polymers

Maintaining high concentrations of microorganisms is crucial for the anaerobic treatment of organics. The granulation of sludge is a good method but it takes more than 6 months to form sludge granules spontaneously. In this study, a large amount of granular sludge was prepared within 5 min by adding organic-inorganic hybrid polymers to the sewage digester sludge. The size of the granular sludge ranged from I to 5 mm and its falling velocity was higher than that of the granular sludge from the actual wastewater treatment facility. Since the granule was stable throughout the operation of a UASB, the removal efficiency was as high as 90% at high organic loading rate up to 18 kg-COD/m(3) day. (C) 2003 Elsevier Ltd. All rights reservedclos

Particle-in-cell simulation of a neutral beam source for materials processing

Neutral beam processing is being considered as a new technique to reduce plasma-induced damage in materials processing. We report on particle-in-cell simulations of a neutral beam source. The system is composed of an ion-beam source and multireflectors which neutralize incident ions and reflect neutral particles. It is revealed from the simulations that about 2.8 % of the ion-current from an ion-beam source is successfully neutralized before reaching a diagnostic plate.close61

Facile Surface Modification and Application of Temperature Responsive Poly(N-isopropylacrylamide-co-dopamine methacrylamide)

The temperature-responsive poly(N-isopropylacrylamide) [PNIPAAm] has been exploited for various biomedical applications. In this work, poly(N-isopropylacrylamide-co-dopamine methacrylamide) [P(NIPAAm-co-DMAAm)] was synthesized for facile surface modification and application to cell sheets. 1H NMR, FT-IR, and GPC confirmed the successful synthesis of P(NIPAAm-co-DMAAm). The lower critical solution temperature was measured to be ca. 29.2 degrees C by UVVis spectroscopy. AFM imaging clearly visualized the transient phase transition of the temperature-responsive polymer bound on silicon substrate by coordination bond formation. Furthermore, the adhesive and temperature responsive P(NIPAAm-co-DMAAm) could be successfully applied to the facile preparation of NIH-3T3 fibroblast cell sheets.X111111sciescopu

Structural versus electronic distortions in IrTe2 with broken symmetry

We investigate atomic and electronic structures of the intriguing low-temperature phase of IrTe2 using high-resolution scanning tunneling microscopy and spectroscopy. We confirm various stripe superstructures such as x3, x5, and x8. The strong vertical and lateral distortions of the lattice for the stripe structures are observed in agreement with recent calculations. The spatial modulations of electronic density of states are clearly identified as separated from the structural distortions. These structural and spectroscopic characteristics are not consistent with the charge-density wave and soliton lattice model proposed recently. Instead, we show that the Ir (Te) dimerization together with the Ir 5d charge ordering can explain these superstructures, supporting the Ir dimerization mechanism of the phase transition.open1198sciescopu

Nanoscale Superconducting Honeycomb Charge Order in IrTe2

Entanglement of charge orderings and other electronic orders such as superconductivity is in the core of challenging physics issues of complex materials including high temperature superconductivity. Here, we report on the observation of a unique nanometer scale honeycomb charge ordering of the cleaved IrTe2 surface, which hosts a superconducting state. IrTe2 was recently established to exhibit an intriguing cascade of stripe charge orders. The stripe phases coexist with a hexagonal phase, which is formed locally and falls into a superconducting state below 3 K. The atomic and electronic structures of the honeycomb and hexagon pattern of this phase are consistent with the charge order nature, but the superconductivity does not survive on neighboring stripe charge order domains. The present work provides an intriguing physics issue and a new direction of functionalization for two-dimensional materials.118sciescopu