Engenharia Química
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/25
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12 resultados
Resultados da Pesquisa
- Effects of caramelization and Maillard reaction products on the physiology of Saccharomyces cerevisiae(2023-01-05) ELIODORO, K. P.; PENNACCHI, C.; DE GOIS E CUNHA, G. C.; Andreia de Araújo Morandim Giannetti; GIUDICI, R.; BASSO, T. O.© 2023 British Mycological SocietyThe thermal treatment the sugarcane juice undergoes during its processing alters the medium's chemical composition through the so-called Maillard reactions and its products, which can affect the alcohol-producing yeast's physiology in steps following the processing. This study aims to describe and characterize the reactivity of the primary amino acids present in sugarcane with sucrose, as well as demonstrate the physiological effects of the reaction's products on the yeast Saccharomyces cerevisiae. The main amino acids in sugarcane (glutamine, asparagine, and aspartic acid) were chosen to be reacted with sucrose under similar conditions to the industrial sugarcane processing (pH 5 and temperature 100–120 °C). The physiological effect of Maillard and caramelization reaction on the S. cerevisiae CEN.PK-122 and PE-2 strains were tested in microplate experiments using a modified mineral media containing both the reacted and unreacted amino acid-sucrose systems and four modified synthetic molasses media. The results have shown that the presence of any amino acids drastically increases product formation. Furthermore, among the amino acids, aspartic acid was the most reactive. Meanwhile, asparagine and glutamine had similar results. In S. cerevisiae physiology, aspartic acid had the most significant effect on culture growth by reducing the maximum specific growth rate and optical density. The increase in the Maillard product concentration for synthetic molasses also evidenced the inhibitory effect on yeast growth compared to media in the absence of these products. We conclude that this initial investigation clarifies the inhibitory effect of the Maillard products on yeast physiology.
- Biocompatibility of polyvinyl alcohol/trisodium trimetaphosphate as vitreous substitute in experimental vitrectomy model in rabbits(2022-02-05) OLIVEIRA, R. A. DE; MURALHA, F. P.; GRUPENMACHER, A. T.; Andreia de Araújo Morandim Giannetti; BERSANETTI, P. A.; MAIA, M.; MAGALHÃES JUNIOR, O.© 2021 Wiley Periodicals LLC.Synthetic hydrogels have been proposed as vitreous substitutes recently. This study aims to evaluate the biocompatibility of polyvinyl alcohol (PVA) crosslinked with trisodium trimetaphosphate (SMTP) hydrogel in rabbit vitrectomized eyes. Seven animals were submitted to pars plana vitrectomy and the vitreous was replaced by PVA/SMTP hydrogel. Optical coherence tomography, fluorescein angiogram, clinical, and electrophysiological (ERG) examinations were analyzed at baseline, on postoperative days 7 and 30. The fellow eye was used as the control group. Hydrogel opacification was observed and ERG recordings were reduced in the hydrogel group in rod response, b-wave cone response and flicker. A histological analysis showed retinal disorganization, presence of multinucleated cells, and intraretinal hydrogel particles. The PVA/SMTP hydrogel showed poor biocompatibility. Novel biomaterials compounds should be analyzed in vivo.
- Synthesis of carboxymethylcellulose from corn straw waste: comparison between pre-treatments with sodium hydroxide and low-cost ionic liquid(2022-03-05) BESSA, B. G.; SANTOS, H. P. DOS; MURAKAMI, V. T.; FANTIM, W. M.; BERGAMO, Y. DE. C.; Andreia de Araújo Morandim Giannetti© 2021, Iran Polymer and Petrochemical Institute.In this work, the possibility of using corn straw to obtain carboxymethylcellulose (CMC) was verified. However, to obtain CMC from lignocellulosic residues, it is necessary to carry out initial treatments to reduce the levels of lignin and hemicellulose. In this context, studies have been conducted to enable the use of an ionic liquid (IL). The n-butylammonium acetate was used to treat the straw instead of the pulping stage for the subsequent attainment of CMC. For comparison, we determined the composition of the resulting material after the stages of NaOH pulping (NaP) or treatment with the IL (at 80 °C—ILP80 and 120 °C—ILP120) and bleaching, to analyze the purity of the cellulose obtained. It was also possible to verify that the treatment at 120 °C was more effective to remove inorganic materials and lignin, leading to cellulose with 91.45 ± 0.11% purity when compared with its treatment at 80 °C. CMC was successfully synthesized and presented similar morphologies accordingly. Consequently, the attainment of CMC was confirmed by analyzing the data obtained via FTIR, NMR, and XRD techniques, as well as the analyses of degree of substitution. It was also possible to recover the ionic liquid at a purity of 95.93%. Graphical abstract: [Figure not available: see fulltext.]
- Spectrophotometric Analysis of Different Polymethyl Methacrylate Filters and their Importance in the Implantation of Corneal Rings(2023-04-24) RODRIGUES, P. F.; MOSCOVICI, B. K.; HOEHNE, J. L.; CAMPOS, M. S. D. Q.; Andreia de Araújo Morandim Giannetti; BERSANETTI, P. A.; NOSE, W.© 2023 Taylor & Francis Group, LLC.Purpose: This study evaluated the luminous behavior applied to materials used in intraocular surgeries. Methods: Discs of the different products were delivered in 19.00 mm × 3.00 mm. Each sample was fixed on support keeping it perpendicular to the spectrophotometer beam. Later, their analyses were carried out in the air/PMMA ratio. The graphs of individual profiles of the measurements along the length were constructed according to each of the filters from the spectrophotometric analysis. In addition, descriptive statistics of transmittance and absorbance for each wavelength presented were correlated for each filter. Results: It is possible to observe that the minimum absorption measure was found in the Red Filter, especially in the blue and green light spectrum. Conclusion: Using filters in PMMA materials appears to improve visual quality in corneal implants, especially the red filter, due to greater absorbance of light leading to fewer light scattering phenomena through corneal rings. However, further studies comparing the effects of different filters on Intracorneal rings should be carried out to elucidate this field of study.
- DSC analysis of the influence of time and concentration of Stryphnodendron adstringens extract on corneal cross-linking(2022-11-11) BERSANETTI, P. A.; MARQUINI, A. A.; Andreia de Araújo Morandim Giannetti© 2022, Akadémiai Kiadó, Budapest, Hungary.Keratoconus is an ectasia that leads to reduced stiffness of the cornea, which acquires a conical shape. Many studies are being carried out aiming at new treatments that lead to the recovery of these cross-links. Therefore, the efficiency of the Stryphnodendron adstringens butanolic extract in promoting cross-linking in corneal stroma of porcine eyes was analyzed. The influence of concentration of this plant extract to form cross-links was analyzed, as well as the influence of the contact time. The denaturation temperature results obtained for corneas treated with 1, 2, or 4% of the barbatimão butanolic extract show an increase of 3.84, 11.37, and 33.23%, respectively. These results suggest a rise in the number of cross-links. As for the contact time of the cornea with the 2% solution of the butanolic extract, it appears that the ideal time was 60 min. Enzymatic digestion assays confirm a decrease of 39% and 59% in the relative area and relative mass of corneas in the control group, while for the group treated with the barbatimão extract, these values were close to 0% and 9%, respectively. Therefore, it was possible to verify the efficiency of the barbatimão butanolic extract in modifying the stroma of porcine corneas, which promoted an increase in resistance to thermal and enzymatic degradation.
- DSC evaluation of cross-link development induced by laccases in corneas(2022-11-25) Andreia de Araújo Morandim Giannetti; CARVALHO, T. S.; DE ANDRADE NETO, J. C.; BERSANETTI, P. A.© 2022, Akadémiai Kiadó, Budapest, Hungary.Several studies have been developed aiming at new treatments for ophthalmological problems such as keratoconus, an eye disease that leads to the reduction of cross-links between the corneal collagen fibrils. Corroborating these studies, this work evaluated the increase of cross-linking in enucleated porcine eyes treated with catechin in the presence of laccase. The ideal conditions for the treatment of the cornea to promote the development of cross-links were determined through the application of a design of experiments. The input variables were the concentration of laccase and the reaction temperature, and the output variable was the enthalpy of corneal denaturation. The DSC results show that the ideal laccase concentration was 8.0 mg mL−1 and the temperature was 36.0 °C. The catechin concentration used was 5.0 mg mL−1. This condition led to a 10.8% increase in the denaturation temperature and a 110.3% increase in the denaturation enthalpy. Enzymatic degradation tests showed that within 24 h of digestion the group treated with laccase in the presence of catechin was more resistant compared to the control group. A decrease of 34.7 and 55.6% in the relative area and relative mass of corneas in the control group was verified, while for the group treated with laccase these values were 41.7 and 8.5%, respectively.
- Phenylalanine ammonia lyase: new insights from Piperaceae species(2022-08-17) Andreia de Araújo Morandim Giannetti; FELIPPE, L. G.; SANTOS, V. AP. de F. F. M. dos; KATO, M. J.; FURLAN, M.© 2022 Atlantis Livros Ltda.. All rights reserved.The enzyme PAL (phenylalanine ammonia lyase) mediates the key entry point to the general phenylpropanoid pathway, which is involved in the lignification process and in the formation of a myriad of secondary compounds in plants that show a variety of biological activities. Soluble fractions containing PAL extracted from Piper and Peperomia species had the optimal catalytic activity analyzed by statistical design model. This analysis revealed that the best conversion of L-phenylalanine to trans-cinnamic acid was pH 9.3 and 58 °C after 25 h, corroborating interesting thermal stability. Additionally, the pre-purification of PAL using ammonium sulfate precipitation (25-55%) increased its specific activity, approximately 133% in P. aduncum and more than 900% in P. crassinervium. The content of lignin was higher for P. tuberculatum (25.71%), while only a small amount of lignin was observed in Peperomia blanda (11.95%). It is interesting to note that Peperomia plants are succulent and without significant amounts of lignin. However, the phenylpropanoid biosynthetic pathway is apparently addressed to produce predominantly tetrahydrofuran lignans with biological interest.
- Peptidases production by fungi obtained from Manihot esculenta Crantz waste and its application in gluten hydrolysis(2021-10-01) GARCIA, V. S.; BERSANETTI, P. A.; Andreia de Araújo Morandim Giannetti© 2021 Elsevier LtdThe growing number of people who develop food intolerance has worried researchers around the world. In this context, studies have been developed to find alternatives that minimize the side effects of these disorders. Positive results have been obtained through the enrichment of foods which contain gluten with specific enzymes able to hydrolyze their protein chains. Therefore, this study investigated fungi associated with stems and leaves of Manihot esculenta Crantz waste which produce peptidases capable of hydrolyzing gluten. The peptidase production capacity of the fungi was tested, and the best results were observed for the ST5 fungus (Alternaria sp.) with specific activity of 1.28 ± 0.004 U/mg. For this fungus, tests were carried out and it was verified that pH 3.0 was the best for its growth using sucrose as a carbon source (2.06 ± 0.001 mg/mg of protein). The pre-purification of the enzyme by saline precipitation with ammonium sulphate showed the best activity (81.69 mg/mg of protein) was achieved in the supernatant obtained after saturation of 75.0%. In the gluten hydrolysis reaction, the ideal reaction time was 24 h and the pH approximately equal to 4. In addition, it was demonstrated that the enzymatic activity involved in gluten hydrolysis was blocked by the inhibitor of aspartyl-peptidase-pepstatin.
- Manufacture of non-thrombogenic polymer surfaces by gamma irradiation to induce simultaneous grafting and heparinization of thin PVC films(2021-07-05) PANZARINI, L. C. G. A.; Andreia de Araújo Morandim Giannetti; GUEDES, S. M. L.© The Author(s) 2021.Investigations regarding alternative methods for producing polymeric materials with hydrophilic properties have increased considerably. In this context, polymeric biomaterials with hemocompatible surface properties have been successfully obtained by grafting hydrophilic monomers onto commercial polymer films by simultaneous irradiation processes. In this study, simultaneous irradiation and grafting were used to produce a copolymer PVC-co-DMAEMA-co-heparin with hemocompatible surface properties. Characterization by FTIR of the graft copolymer indicates that the increase in monomer grafting levels inhibits the bonding sites to heparin. FTIR-PAS analyses of the graft copolymers showed that the highest graft levels were obtained for the irradiated samples containing 45% of monomer. Heparin, however, could only be detected in the irradiated samples containing 30% of DMAEMA. The analysis of the micrographs, on the other hand, showed that increasing the monomer concentration enhances surface roughness of the graft copolymers. Roughness however decreased with heparin addition. It was possible to verify that an excess of surface roughness of the graft copolymers inhibits anticoagulant properties of heparin, triggering thrombus formation. Platelet adhesion, on its turn, was not significantly affected by the presence of heparin when PVC-co-DMAEMA and PVC-co-DMAEMA-co-heparin, obtained from the systems containing 45% of monomer, are compared. The addition of heparin in the systems containing 30% of DMAEMA resulted in fewer thrombogenic surfaces.
- Evaluation of Purple Onion (Allium cepa L.) Extract as a Natural Corrosion Inhibitor for Carbon Steel in Acidic Media(2021-09-05) GALO, T. A.; Andreia de Araújo Morandim Giannetti; COTTING, F.; AOKI, I. V.; AQUINO, I. P.© 2020, The Korean Institute of Metals and Materials.Abstract: The capacity of the Allium cepa L. extract from peel (ACP) and bulb (ACB) as a natural corrosion inhibitor for carbon steel was evaluated. The corrosion characterization was performed by a gravimetric test, showing an inhibitor efficiency of 60% (ACP) and 67% (ACB). Electrochemical tests indicated higher corrosion resistance for carbon steel in the presence of the extracts, and the SEM images of steel samples confirm the results. These extracts were analyzed by the DPPH (2,2-diphenyl-1-picrylhydrazyl) method, confirming the antioxidant activity. The chemical characterization of the extracts by FTIR measurements revealed the presence of phenolic compounds with antioxidant capacity. Graphic Abstract: [Figure not available: see fulltext.]