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The aim of this work was to synthesize pinus residue/pectin-based composite hydrogels for the immobilization of β-D-galactosidase. These hydrogels were synthesized via chemical crosslinking, and characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, thermal analysis, mechanical assays, X-ray diffraction, and swelling kinetics. The water absorption mechanism in the hydrogel networks occurs by non-Fickian transport. The β-D-galactosidase immobilization capacities of the hydrogels containing 0, 5 and 10% of pinus residue were respectively 242.08 ± 0.36, 181.27 ± 0.50 and 182.71 ± 0.36 mg enzyme per g dried hydrogel, at pH 4.0 and after 600 min. These values were 182.99 ± 0.41, 219.99 ± 0.47 and 218.56 ± 0.39 mg g−1, respectively, at pH 5.6. Pectin-based hydrogels demonstrated to be excellent solid supports for the immobilization of enzymes. β-D-Galactosidase immobilized in pectin-based hydrogels could be applied in the hydrolysis of lactose contained in either dairy foods or lactose-intolerant individuals.

Cellulose is a renewable, sustainable, and high available biopolymer; their common form is the type-I polymorph. However, polymorphic changes are associated with different properties and a wide range of applications. In this study, we proposed a new method to prepare polymorphic cellulose nanostructures (CNSs): first, the CNS were isolated, and then the polymorphs were converted. CNS-I (type-I), CNS-II (type-II), and CNS-III (type-III) were successfully obtained, and the structure, crystallinity, superficial characteristic, morphology, and thermal stability were evaluated. The results showed that CNS-II and CNS-III are more amorphous than CNS-I due to the strong reagents used for the polymorphic conversion, which results in a swelling, increased chain spacing, and structural disorganization. This effectively changed the morphology of the CNS, from cellulose nanocrystals from irregular quasi-spherical nanoparticles. The proposed method allows a wide range of applications, from package and nanocomposites with CNS-I due to its high crystallinity and crystal morphology, to drug carrier, food thickener and biomedical products for CNS-II and CNS-III due to its quasi-spherical shape and more amorphous structure.

In this work, it was studied the steric and electrostatic stabilization of cellulose nanostructures (CNS) and their effects on the thermal stability of the nanoparticles. Three different agents modified the surface of CNS: a grafted polymer, polyethylene glycol (PEG), a nonionic surfactant, Ultraric, and an anionic surfactant (Surfom). All modifications changed the dimensions of the nanoparticles, and the thermogravimetric results show an improvement in the thermal stability of the CNSs, that is, the thermal decomposition of cellulose increased from 326 to 341–366 °C for Surfom-modified samples, 348–389 °C for Ultraric-modified samples, and to 426–436 °C for PEG-modified samples. The differential scanning calorimetry showed that the Surfom-modified samples have no crystalline structure, different from the other modifiers. The other stabilizers showed a tendency to form a crystalline coating in the CNSs surface since all the results are highly dependent on the structure of the modified. In this way, it is possible to conclude that the addition of different materials to improve the stabilization of CNS and minimize its aggregation tendency has a significant influence on the thermal stability, enhancing the applicability of these nanomaterials. Finally, it is presented how the differences between the thermal behavior of the modified CNS impact the applications, comparing the use of different polymer matrices and its respective processing temperatures.

The stabilization of nanocellulose suspensions and their compatibility with polymer matrices are challenges that have been investigated in the scientific community. However, little work has resulted in significant electrostatic stabilization as well as improved the mechanical behavior of nanocomposites. Anionic surfactant modified nanocellulose, and the results demonstrated the impact of the concentration of this surfactant on nanocellulose surfaces and properties. The variation in electrostatic stability was evaluated by the zeta potential, which is key to the comprehension of dispersion and agglomeration in suspensions. Also, physicochemical tests were conducted to analyze the properties of nanocelluloses. The addition of the surfactant and its effects were verified by physicochemical characterization; it was evaluated the crystallinity, thermal stability, composition, adsorption effect, and other properties. Mechanical, thermal and physicochemical tests were conducted to understand the influence of nanoparticles on nanocomposites. The results of this study demonstrated that the surfactant-modified cellulose nanostructures presented excellent electrostatic and thermal stability, which made the developed materials potential reinforcing agents for the incorporation of polymeric matrices. These modified CNSs were incorporated in a poly(butylene adipate-co-terephthalate), and improvements of its mechanical properties were observed. Also, the thermal stability of the polymer was maintained, and the water diffusion coefficient was reduced, favoring applications that need this characteristic, like plastic packaging.

In recent year, the interest in environmentally friendly materials, like cellulose nanostructures (CNSs) has increased. Nanoscale dimensions, high surface area, low density, and high mechanical strength are examples of CNSs properties that attract researchers' attention. CNSs stability and dispersity are the main limitations that prevent its application as nanofiller in polymeric matrices. In this work, the surface modification of CNSs was investigated. To overcome CNSs limitation, they were modified with polyethylene glycol (PEG), in aqueous solution, in different proportions: 2, 5 and 10 wt%. FTIR, elemental analysis, NMR, and XPS were carried out to verify the adsorption efficiency. The results showed an excellent adsorption of PEG chains on the CNSs surface, with particle size increase of 50–90 nm and a considerable increase in thermal stability. XRD and AFM analysis observed no significant variation in crystallinity and morphology in modified CNSs. Thus, modification of CNSs with PEG is an environmentally friendly process and showed positive results regarding improving CNSs stability, in aqueous media.

In this work, carboxymethyl cellulose (CMC) hydrogels were produced via chemical crosslink with citric acid and filled with nanocellulose (NC), montmorillonite, or vermiculite, in different contents. The FTIR results indicated a strong chemical interaction between NC or vermiculite and the CMC, increasing the hydrogen bond energies by the fillers' participation in the crosslinking, reflecting in the water absorption (WA). Higher filler contents interacted more with the matrix, resulting in a denser hydrogel with lower WA capacity. The montmorillonite did not alter the hydrogels' structure due to its low compatibility with the CMC, doubling the WA values at low contents. The hydrogels' thermal stability was maintained after the fillers' addition. NPK fertilizer was added to selected formulations, and results indicated success in NPK encapsulation. Fertilizer release in water and soil indicated a slow-release, and the rate was dependent on the filler; all fillers showed a low rate than the CMC pristine hydrogel. The Korsmeyer-Peppas model indicated that vermiculite is not adequate for agriculture applications due to the diffusion mechanism, while nanocellulose and montmorillonite showed crucial results for the field. The in vivo tests demonstrate hydrogels' efficiency filled with 3% NC or 1% montmorillonite in the nutrients-controlled release.

Arabic gum-based composite hydrogels reinforced with eucalyptus and pinus residues were synthesized via free-radical reaction aiming to controlled phosphorus release. All hydrogels were characterized by swelling kinetics (SK), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-Ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mechanical assays (MA). The water and solute transports through the hydrophilic three-dimensional networks of the hydrogels occur preferably by diffusion processes and macromolecular relaxation. Hemicellulose, lignin and cellulose fibers contained in eucalyptus and pinus residues affected the crosslinking density, crystalline structure, and water/solute diffusion due to reduction of free hydroxyl and amine groups in the hydrogel networks. Hence, the eucalyptus and pinus residues improved the mechanical and thermal resistances of the composite hydrogels. Finally, the Arabic gum-based hydrogel and Arabic gum-based composite hydrogels reinforced with eucalyptus and pinus residues demonstrated to be excellent alternatives for the controlled phosphorus release in agricultural nutrient-poor soils.

Made available in DSpace on 2020-12-12T01:06:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 This study aimed to explore the use of eucalyptus sawdust for the extraction of nanocellulose. This residue was purified with a three-steps pretreatment and ball milled for the isolation of nanocellulose. The method proposed can be industrially applied due to the use of reactor and ball mill and can be used for a variety of cellulose sources. Cellulose was the main component detected in the eucalyptus residues, as observed after the characterizations. The nanostructures showed an average size of 192 nm and high crystallinity and thermal stability. The current study demonstrated that the nanocellulose could be obtained to commercial-scale applications. Engineering Modeling and Applied Social Sciences Center (CECS) Federal University of ABC Department of Biotechnology Lorena Engineering School University of São Paulo School of Agriculture São Paulo State University (UNESP) School of Agriculture São Paulo State University (UNESP)

Standig wechselnde Kost wirkt reizend auf den reticuloendothelialen Apparat und vermag innerhalb gewisser Grenzen eine Resistenzsteigerung gegen das Angehen und das Wachstum von Transplantationsgeschwulsten hervorzurufen.

Previous papers have supported the hypothesis that beta-agonist drugs could accumulate in those tissues with a high content of mucopolysaccharides. Based on our preliminary findings, between October and December 1993 we randomly sampled 534 samples of synovial fluids drawn from the knee joint of fresh carcasses. After a preliminary extraction able to break down the water domains of mucopolysaccharides and the interactions between the matrix and the drugs, samples were concentrated on diatomaceous earth and then screened on two different ELISA plates. We confirmed the structure of suspected fluids by GC-MS (HFBA derivatization), according to EC criteria. Of the 57 samples screened as positive (10.6% of the total), 51 (9.5%) were fully confirmed, while for six it was not possible to identify the drug. The results suggest that the analysis of synovial fluids is an adequate tool to monitor the misuse of beta-adrenergic drugs in animal production, especially when target organs such as liver and kidney are not available for sampling.