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Sputtering of micro-carbon-silver film (μC-Ag) for endotracheal tubes to mitigate respiratory infections
(IOP science) Silva, Michely Glenda Pereira da; Manfroi, Lucas Augusto; Lobo, Larissa Zamboni; Vieira, Angela Aparecida; Macário, Paulo Fabrício; Fukumasu, Newton Kiyoshi; Silva, Newton Soares da; Tschiptschin, André Paulo; Marques, Francisco das Chagas; Vieira, Lucia
Polyurethane (PU) substrates are biocompatible materials widely used to manufacture endotracheal tubes. However, in common with other biomedical materials, they are liable to the formation of microbial films. The occurrence of pneumonia in intubated patients treated at intensive care units often takes the form of ventilator-associated pneumonia (VAP). The issue relates to the translocation of pathogenic microorganisms that colonize the oropharyngeal mucosa, dental plaque, stomach, and sinuses. New protective materials can provide a more effective therapeutic approach to mitigating bacterial films. This work concerns microcrystalline carbon film containing dispersed silver nanoparticles (μC-Ag) deposited on PU substrates using a physical vapor deposition sputtering process. For the first time, carbon paper was used to produce a carbon target with holes exposing a silver disk positioned under the carbon paper, forming a single target for use in the sputtering system. The silver nanoparticles were well distributed in the carbon film. The adherence characteristics of the μC-Ag film were evaluated using a tape test technique, and electron dispersive x-ray mapping was performed to analyze the residual particles after the tape test. The microbicidal effect of the thin film was also investigated using species S. aureus, a pathogenic microorganism responsible for most infections of the lower respiratory tract involving VAP and ventilator-associated tracheobronchitis (VAT). The results demonstrated that μC-Ag films on PU substrates are promising materials for mitigating pathogenic microorganisms on endotracheal tubes.
Enhancing UV Radiation Resilience of DLC-Coated Stainless Steel with TiO2: A Dual-Layer Approach
(MDPI) Macário, Paulo Fabrício; Silveira, Carolina Hahn da; Vieira, Angela Aparecida Moraes; Marcondes, André Ricardo; Marques, Francisco das Chagas; Fechine, Guilhermino José Macêdo; Vieira, Lucia
This study presents an innovative dual-layer coating approach integrating titanium dioxide (TiO2) onto diamond-like carbon (DLC)-coated 316L stainless steel. The combination of PECVD- deposited DLC and ALD-deposited TiO2 aims to preserve the inherent tribological properties of DLC while mitigating UV-induced degradation. By leveraging the ability of TiO2 to absorb, reflect, and scatter UV light, this dual-layer strategy significantly enhances the durability of DLC coatings in radiation-prone environments. The effects of accelerated aging through UV exposure on DLC and DLC/TiO2 films were evaluated using an Accelerated Weathering Tester. Comprehensive analyses were conducted to assess the structural and mechanical properties before and after UV exposure, including Raman spectroscopy, profilometry, SEM, EDS, nanoindentation, and tribometry. The results demonstrate that the TiO2 layer effectively mitigates UV-induced damage, preserving the DLC film’s integrity and tribological performance even after 408 h of UV aging. Specifically, the DLC/TiO2 coatings maintained lower roughness, higher hardness, and better adhesion than DLC- only coatings under identical conditions. This research significantly advances protective coating technology by enhancing the durability and performance of DLC films, particularly in aerospace and other demanding industries where exposure to UV radiation is a critical concern.
Influence of manufacturing parameters on bioactive glass 45S5: Structural analysis and applications in bone tissue engineering
(Elsevier) Santos, Kennedy Wallace dos; Costa, Karen Julie Santos Grancianinov; Gonçalves, Isabela dos Santos; Alves, M.; Lauda, Diogo Ponte; Vasconcellos, Luana Marotta Reis de; Campos, Tiago Moreira Bastos; Oliveira, Ivone Regina de
Bioactive glass (BG-45S5) production through the melting process is affected by a wide variety of parameters. This study investigated the synthesis of BG-45S5 granules and the process variables to produce a bioactive and osteoinductive BG for bone grafting applications. The melting process was initially analyzed by varying pa- rameters such as crucible type and pouring environment using P2O5 as phosphorus precursor. The obtained products were characterized by crystalline phases, characteristic chemical groups, particle size distribution, and chemical composition. Materials poured into graphite or steel molds resulted in particle sizes more suitable for applications in granular form. Using a platinum crucible yielded a chemical composition closer to the target when compared with another ceramic crucible. Subsequently, the melting process was evaluated to different phosphorus precursor (P2O5 or Na2HPO4) and melting duration (1 or 2 h) in a platinum crucible verifying their effects on the thermal behavior, chemical composition and structure of BG-45S5. Employing Na2HPO4 as a precursor led to higher glass transition and crystallization temperatures as compared to P2O5, enhancing glass homogeneity and structural stability. The product with better characteristics in terms of composition and structure was further characterized for bioactivity and cell culture behavior, showing a greater amount of mineralization nodules when compared to commercial hydroxyapatite. This is particularly due to its behavior as the solubility and interaction in biological environments.
Characterization of Microporous Ceramics Based on Calcium Hexaluminate “In Situ” Produced by Direct Molding
(Universidade Federal de São Carlos) Leite, Vitória Marques Cesar; Salomão, Rafael; Cardoso, Gustavo Luiz Bueno; Ortega, Fernando dos Santos; Oliveira, Ivone Regina de
Calcium hexaluminate (CA6) presents a wide application in high-temperature thermal insulation. Despite the high porosity levels achieved, the use of carbonated precursors in its synthesis inevitably produces CO2 as a by-product. CA6 was produced by combining different sources of alumina (α-Al2O3 and ρ-Al2O3) and lime (CaCO3, Ca(OH)2, and CaO) in aqueous suspensions that were cast and sintered to evaluate these routes on its physical properties. The products attained after sintering at 1550 and 1600 °C were characterized for crystal phases, real density, particle morphology, uniaxial compressive strength, apparent porosity, and pore size distribution. Part of the samples sintered at 1600 °C was subjected to a thermal shock test and was then evaluated for residual strength under diametrical compression, apparent porosity, pore size distribution, and flexural elastic modulus. The CA6 samples produced from α-Al2O3 presented lower pore fraction and higher mechanical strength and modulus of elasticity. The superior properties of the materials produced with α-alumina were maintained after thermal shock. The acicular geometry of the CA6 particles is related to their excellent thermal shock resistance and mechanical performance. The results indicated a more environmentally friendly system produced from α-Al2O3-CaO for industrial applications of high-temperature thermal insulation resistant to thermal shock damage.
Estudo de propriedades de pastas de cimento Portland modificadas com nanopartículas de dióxido de titânio
(Universidade do Vale do Paraíba) Santos, Elias Barros; Lencioni, Julia Wippich; Paschoal, Alexandre Rocha; Ribeiro, Paulo Henrique; Moura, Thiago Alves de
A durabilidade é um parâmetro importante para estruturas a base de cimento Portland expostas a ambientes agressivos. Neste sentido, o objetivo do presente trabalho foi investigar a influência da adição de nanopartículas de dióxido de titânio (TiO2NPs) nas propriedades de pastas do cimento Portland. Para esta finalidade, foram preparados três tipos de pastas. Os corpos de prova das pastas foram nomeados de CP0, para a pasta de referência sem TiO2NPs, e de CP01 e CP05, para as pastas contendo TiO2NPs nas concentrações de 0,1 e 0,5% em relação à massa de cimento Portland, respectivamente. As partículas de TiO2NPs utilizadas apresentaram tamanho variando entre 20 a 45 nm. As análises de mapeamento Raman e microscopia eletrônica de varredura confirmaram a presença das TiO2NPs dispersas nas pastas. Os resultados do ensaio de compressão axial mostraram que a adição de TiO2NPs não afetou a resistência mecânica dos corpos de prova. Porém, demonstraram influência na resistência a penetração de cloretos. Esta resistência foi dependente da porcentagem de TiO2NPs na pasta sendo maior para as amostras CP05. Da mesma forma, também foi observada uma melhora na resistência ao ataque ácido com o aumento do conteúdo de TiO2NPs. Com isso, conclui-se que a adição de TiO2NPs na composição das pastas de cimento Portland pode contribuir para aumentar a sua durabilidade em meios agressivos.
Strontium- and bioactive glass-enriched dentin repair cement: Mechanical performance and physicochemical characteristics
(Elsevier) Tavella-Silva, Nathalia Cristina; Raucci, Larissa Moreira Spinola Castro; Polizeli, Victor Miguel; Miranda, Carlos Eduardo Saraiva; Oliveira, Ivone Regina de; Raucci Neto, Walter
The aim of this study was to evaluate the effect of strontium (Sr2+) and varying concentrations of bioactive glass (BG) on the physicochemical and mechanical properties of calcium aluminate cement (CAC). The experimental groups included: control (CAC); CAC with 5 wt% BG (CAC5); CAC with 10 wt% BG (CAC10); CAC with 1 wt% Sr2+ (CAC-Sr); CAC5 with 1 wt% Sr2+ (CAC5-Sr); and CAC10 with 1 wt% Sr2+ (CAC10-Sr). Setting time (ST), solubility (SL), pH, electrical conductivity (CON), total dissolved solids (TDS), calcium ion release (Ca2+), radiopacity (RAD), surface roughness (SR), and bond strength (BS) were evaluated using cement discs. ST and RAD were assessed in freshly prepared samples. SL was determined by measuring the weight change of the specimens after seven days of water immersion. pH, CON, TDS, and Ca2+ were quantified in the immersion solutions. SR was measured after 7 and 28 days in water and phosphate-buffered saline (PBS), and BS was evaluated using the push-out test. Data were analyzed using one-way ANOVA and Tukey’s post hoc test (α = 0.05). BG incorporation significantly reduced ST, whereas Sr2+ had no effect. All groups showed mass gain. No significant differences in pH were observed among groups. CAC and CAC5 exhibited higher Ca2+ release than CAC-Sr and CAC5-Sr (p < 0.05). No differences in RAD were found. BS increased with the addition of BG and Sr2+, except in the CAC10-Sr group. Sr2+ enhanced BS in CAC (p < 0.001), but not in CAC5. Failure modes were predominantly mixed and cohesive. In conclusion, BG improved bond strength and reduced setting time, while Sr2+ had no significant effect on the physicochemical properties of the cement.
Balancing thermal conductivity, dielectric, and tribological properties in polyamide 1010 with 2D nanomaterials
(Willey) Pinto, Gabriel Matheus; Staffa, Lucas; Helal, Emna; Hahn, Carolina; Vieira, Lúcia; Ribeiro, Hélio; David, Eric; Demarquette, Nicole Raymonde; Fechine, Guilhermino José Macêdo
Low electrical conductivity and high heat dissipation are crucial for electronic packaging materials. Additionally, friction is critical for the lifespan and energy efficiency of components. To address these requirements, polymer nanocomposites based on bio-based polyamide 1010 and ultra-low contents of 2D nanomaterials were produced by melt-blending. Graphene oxide, hexago- nal boron nitride, and molybdenum disulfide were selected for their two- dimensional structure and electrical insulation, providing high thermal conductivity while preserving the polymer's dielectric nature. Hybrid nanocomposites were also produced to explore potential synergistic effects. Results showed all compositions maintained the polymer's intrinsic dielectric properties. Although the friction coefficient increased slightly compared with neat polyamide, all nanocomposites remained within the low-friction range required for low-friction materials. Thermal conductivity improved by 5%–10% compared with unfilled polyamide, with hybrid systems performing slightly better, indicating a minor synergistic effect. Despite these enhancements being modest compared with the literature, achieving high thermal conductivity usu- ally requires over 20 wt% of nanofiller, which is detrimental to mechanical per- formance. In this study, at most 0.5 wt% was used, with composites being obtained directly through melt-blending. This highlights their potential as low- content additives for thermal interface materials without compromising other essential properties.
Study of (12Co–4Cr WC) and (Cr3C2–25NiCr) coatings sprayed by the HVOF process and subsequently laser remelted
(UFSCar) Oliveira, Ana Claudia Costa; Carvalho, Edinelson; Dyer, Paulo; Silva, Maria Margareth da; Vieira, Lucia; Silveira, Carolina Hahn da; Vasconcelos, Getúlio de
The laser remelting technique on tungsten carbide (12Co–4Cr WC) and chromium carbide (Cr3 C2 –25NiCr) coatings deposited by HVOF provides improvements in surface properties, such as increased hardness and resistance to abrasive wear. This process uses a laser beam to selectively melt the coating, promoting a uniform and adherent layer. In the present work, tungsten carbide and chromium carbide alloy coatings were deposited on properly prepared SAE 1020 substrates using the high-speed oxy-fuel (HVOF) technique. After deposition, the coatings were remelted with a laser beam, varying the scanning speed and the laser beam power of the ytterbium fiber to obtain a pore- and crack-free coating and better metallurgical anchorage to the substrate. The samples were characterized by scanning electron microscopy (SEM), X-ray diffractogram, ASTM G132 Standard Test Method for Pin Abrasion Testing wear and microhardness. The results show that it was possible to obtain coatings with greater hardness after the laser remelting process, reducing pores or imperfections and metallurgically bonding to the substrate.
Effects of graphene nanoplatelets dispersion on the mechanical properties of epoxy resin and carbon fiber laminated composites
(Sage) Donda, Giovanni Moreira; Ortega, Fernando dos Santos; Xavier, Gabriel Doria; Lima, João Vitor Feo; Ricardo, Fernando Valente; Passador, Fabio Roberto; Oliveira, Ivone Regina de
Graphene-related materials (GRM) show great potential as reinforcement in polymeric matrices, offering enhanced physicochemical and mechanical properties. In the aerospace sector, reinforced composites are increasingly used for their superior mechanical attributes and design flexibility. Incorporating graphene nanoplatelets (GNP) into epoxy resin (ER) is a promising approach to enhance the resin’s fracture toughness. The effectiveness of these nanocomposites depends heavily on the dispersion of nanoparticles within the matrix. Therefore, this work aimed to produce nanocomposites based on ER and GNP by evaluating different mixing processes and assessing the influence of GNP content on the resin ́s properties, to determine the optimal conditions for the incorporation GNP-ER as matrix to produce hybrid laminated composites with carbon fiber fabric. Characterization of GNP powder revealed its organization in regular nanoplatelet stacking patterns, exhibiting multilayers with few defects. The characterization of nanocomposites showed that ultrasonication dispersion improved the dispersion of GNP in the resin, reducing agglomerates and increasing homogeneity. Tensile tests dem- onstrated that ultrasonication led to an increase of approximately 14% in the ultimate tensile strength (UTS) and up to 46% in the deformation at the break of the nanocomposites. Carbon fibers/GNP-ER composites were produced by the hand lay- up process and exhibited a decrease in UTS with the addition of GNP, suggesting that GNP may have acted as stress concentrators or even modified the viscosity of the matrix, which may have hindered the matrix ́s ability to penetrate the carbon fabric, thereby reducing the mechanical properties.
Polyelectrolytic gelatin nanoparticles as a drug delivery system for the promastigote form of Leishmania amazonensis treatment
(Taylor & Francis) Souza, Catarina de; Carvalho, Janicy Arantes; Abreu, Alexandro da Silva; Paiva, Lucas Prudente de; Ambrósio, Jéssica Aparecida Ribeiro; Beltrame Junior, Milton; Oliveira, Marco Antonio de; Mittmann, Josane; Simioni, Andreza Ribeiro
In this study, phthalocianato[bis(dimethylaminoethanoxy)] silicon (NzPC) was loaded onto gelatin nanoparticles functionalized with polyelectrolytes (polystyrene sulfonate/polyallylamine hydrochlor- ide) by layer-by-layer (LbL) assembly for photodynamic therapy (PDT) application in promastigote form of Leishmania amazonensis treatment. The process yield, and encapsulation efficiency were 80.0% ± 1.8 and EE 1⁄4 87.0% ± 1.1, respectively. The polyelectro- lytic gelatin nanoparticles (PGN) had a mean diameter of 437.4±72.85nm, narrow distribution size with a polydispersity index of 0.086. The obvious switching of zeta potential indicates successful alternating deposition of the polyanion PSS and polyca- tion PAH directly on the gelatin nanoparticles. Photosensitizer photophysical properties were shown to be preserved after gel- atin nanoparticle encapsulation. The impact of the PDT in the via- bility and morphology of Leishmania amazonensis promastigote in culture medium was evaluated. The PGN-NzPc presented low tox- icity at the dark and the PDT was capable of decreasing the via- bility in more than 80% in 0.1mmol.L 1 concentration tested. The PDT also triggered significant morphological alterations in the Leishmania promastigotes. These results reinforce the idea that the use of PGN as photosensitizers carriers is useful for PDT of Leishmania promastigotes.
Combined morphological-compositional analysis of the interaction of collagen and chitosan based-materials with demineralized bovine dentin
(Brazilian Journals Publicações de Periódicos) Nahórny, Sidnei; Oliveira, Ivone Regina de; Soares, Luís Eduardo Silva
Treatments to promote the biomineralization of dentin are the focus of much research with different materials and processes. Biomineralization is a process mediated by an organic matrix in which organic macromolecules act as models for the nucleation and growth of mineral crystals to form hierarchically ordered hybrid materials, such as bones or teeth. This study describes the application of novel materials based on collagen and chitosan aimed to protect the dentin from erosive conditions. The dentin morphology of the bovine teeth treated with these materials was visualized using scanning electron microscopy (SEM). In additions, it was possible to confirm the data by analyzing the distribution of inorganic content of dentin by micro energy-dispersive X-ray fluorescence spectrometry (µ-EDXRF). The association of analytical techniques demonstrated greater surface coverage for the chitosan-fluoride followed by the hydrolyzed collagen. Both materials are promising for the application of dentin coverage in dentistry.
SiOx Top Layer on DLC Films for Atomic Oxygen and Ozone Corrosion Protection in Aerospace Applications
(Universidade Federal de São Carlos) Ferreira, Leandro Lameirão; Radi, Polyana Alves; Silva Sobrinho, Argemiro Soares da; Vieira, Lucia; Leite, Douglas Marcel Gonçalves; Recco, Abel Andre Candido; Reis, Danieli Aparecida Pereira; Massi, Marcos
Every year, billions of dollars are invested in research and development for space applications, including new systems, new technologies, and new materials. DLC (Diamond-Like Carbon) is a promising material for use in these applications, but its use faces a technological barrier, since it is severely etched by atomic oxygen and ozone. In this study, SiOx-DLC thin films were deposited as a top layer of diamond-like carbon (DLC) films on Ti-6Al-4V substrates to increase resistance against corrosion by atomic oxygen and ozone as well as meet the requirements for use in Low Earth Orbit (LEO) satellites. The corrosion resistance of the films was evaluated using oxygen plasma, and the tribological and mechanical properties were investigated. The SiOx-DLC top layer reduced the corrosion rate two orders of magnitude and increased the critical load from 16.2 ± 1.5 N to 18.4 ± 0.4 N.
Replacement of the carbon catabolite regulator (cre1) and fed-batch cultivation as strategies to enhance cellulase production in Trichoderma harzianum
(Elsevier) Delabona, Priscila da Silva; Lima, Deise Juliana; Codima, Carla Aloia; Ramoni, Jonas; Gelain, Lucas; Melo, Vandierly Sampaio de; Farinas, Cristiane Sanchez; Pradella, José Geraldo da Cruz; Seiboth, Bernhard
This work focused on mitigating carbon catabolic repression (CCR) and increasing cellulase production in Trichoderma harzianum based on the cre1 deletion. The CRE1 protein (encoded by cre1) has been described as a cellulase transcriptional repressor in various cellulotic fungi, but has not been investigated in T. harzianum. We constructed ∆cre1 T. harzianum by replacing the cre1 gene with the amdS gene from Aspergillus nidulans. Quantitative PCR analysis of some Cazymes genes showed that CRE1 acts positively on gh61, bgl1 and xyn2. The fed-batch strategy using hydrothermal sugarcane bagasse by the ∆cre1_Th15 produced a constant rate of FPase under glucose influence, suggesting that the knockout of the carbon catabolite regulator improved the glycoside hydrolases (FPase 1.96 ± 0.32 IU/mL; β-glucosidase 5.67 ± 0.28 IU/mL and xylanase 327. 26 ± 14.25 IU/mL), so that this strain can be used for biorefinery purposes.
High-Tribological-Performance Polymer Nanocomposites: An Approach Based on the Superlubricity State of the Graphene Oxide Agglomerates
(MDPI) Ferreira, Eder Henrique Coelho; Vieira, Angela Aparecida; Vieira, Lucia; Fechine, Guilhermino José Macêdo
Here, nanocomposites of high-molecular-weight polyethylene (HMWPE) and HMWPE- UHMWPE (80/20 wt.%) containing a low amount of multilayer graphene oxide (mGO) (≤0.1 wt.%) were produced via twin-screw extrusion to produce materials with a higher tribological performance than UHMWPE. Due to the high viscosity of both polymers, the nanocomposites presented a signifi- cant concentration of agglomerates. However, the mechanical (tensile) and tribological (volumetric loss) performances of the nanocomposites were superior to those of UHMWPE. The morphology of the nanocomposites was investigated using differential scanning calorimetry (DSC), microtomogra- phy, and transmission electron microscopy (TEM). The explanation for these results is based on the superlubricity phenomenon of mGO agglomerates. It was also shown that the well-exfoliated mGO also contained in the nanocomposite was of fundamental importance as a mechanical reinforcement for the polymer. Even with a high concentration of agglomerates, the nanocomposites displayed tribological properties superior to UHMWPE’s (wear resistance up to 27% higher and friction co- efficient up to 57% lower). Therefore, this manuscript brings a new exception to the rule, showing that agglomerates can act in a beneficial way to the mechanical properties of polymers, as long as the superlubricity phenomenon is present in the agglomerates contained in the polymer.
Enamel erosion prevention and mechanism: effect of 10.6-μm wavelength CO2 laser low power density irradiation studied by X-ray fluorescence and infrared spectroscopy and scanning electron microscopy
(Springer Nature Link) Lopes, Francialza Veras Viana; Sanches, Roberto Pizarro; Vasconcelos, Getúlio de; Bhattacharjee, Tanmoy T.; Santo, Ana Maria do Espírito; Soares, Luís Eduardo Silva
Purpose This study assessed the effects of carbon dioxide (CO2) laser (λ = 10.6 μm, 5 W, 70 J/cm2) irradiation alone and after treatment with neutral fluoride gel on enamel and their efficacy in preventing enamel erosion compared to untreated and fluoride gel-treated enamel. Methods Enamel surfaces of the bovine incisor (n = 7/group) were treated with artificial saliva (S, negative control), neutral fluoride (NF, positive control), CO2 laser irradiation (L), and NF + laser (NF + L). Samples were acid demineralized (soft drink, pH ~ 3.2, 10 min), remineralized (saliva, 37 °C, 1 h), and analyzed using micro-energy-dispersive X-ray fluorescence spectrom- etry (μ-EDXRF), attenuated total reflectance–Fourier-transform infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy (SEM). Results Results suggest that NF gives the best protection against erosion, followed by NF + L and L. μ- EDXRF showed that changes due to laser treatment in L and NF + L were uneven. SEM images showed morphological changes in L and NF + L such as craters, fissures, and roughness in some regions, again indicating the unevenness of laser-induced enamel changes. ATR-FTIR mean spectra intensity levels and principal component analysis also indicate higher efficacy of fluoride over laser treatments and unevenness of laser treatments. Conclusion Overall, it can be concluded that CO2 laser parameters need to be further investigated to promote adequate protection with minimum surface changes.
Ionizographic detector for Breast Cancer Diagnosis
(CDRR Editors) Matos, Helton Gírio; Ramos, Marco Antonio Ramirez; Vieira, Lúcia; Pires, Ary Oliveira
Every day the number of cancer victims increases. In 2020 alone, 626,030 people were affected in Brazil, according to estimates by the National Cancer Institute (INCA). The only way to reduce these numbers is early diagnosis. In the present study, a invention called Ionizographic Detector is described, which performs Positron Emission Tomography (PET) producing metabolic information in breast nodules. This device enables accurate diagnosis of breast nodules regarding its malignancy. To prove its effectiveness, a comparative evaluation was made between the Ionizographic Detector and the Positron Emission Tomography/Computerized Tomography (PET-CT) for analysis of the metabolic data in breast nodules. The research is being carried out with 20 patients who have histopathologically documented breast cancer. From the results it will be possible to prove the device’s efficacy. It will thus enable an accurate and low-cost malignancy diagnosis option. The Ionizographic Detector can be hybridized with some anatomical imaging technology, such as Ultrasound (US). With this, it is possible to promote greater access to accurate diagnoses, significantly increasing the possibility of early diagnoses, enabling a cure or a better prognosis for the patient.
Continuous production of enzymes under carbon-limited conditions by Trichoderma harzianum P49P11
(Elsevier) Gelain, Lucas; Kingma, Esther; Pradella, José Geraldo da Cruz; Costa, Aline Carvalho da; Wielen, Luuk Van Der; Gulik, Walter Martin van
Carbon-limited chemostat cultures were performed using different carbon sources (glucose, 10 and 20 g/L; sucrose, 10 g/L; fructose/glucose, 5.26/5.26 g/L; carboxymethyl cellulose, 10 g/L; and carboxymethyl cellulose/glucose, 5/5 g/L) to verify the capability of the wild type strain Trichoderma harzianum to produce extracellular enzymes. All chemostat cultures were carried out at a fixed dilution rate of 0.05 h . Experiments using glucose, fructose/glucose and sucrose were performed in duplicate. Glucose condition was found to induce the production of enzymes that can catalyse the hydrolysis of p-nitro- phenyl-b-D-glucopyranoside (PNPGase). A concentration of 20 g/L of glucose in the feed provided the highest productivity (1048 ± 16 U/mol h). Extracellular polysaccharides were considered the source of inducers. Based on the obtained results, a new PNPGase production process was developed using mainly glucose. This process raises interesting possibilities of synthesizing the inducer substrate and the induced enzymes in a single step using an easily assimilated carbon source under carbon-limited conditions.
Bioactivity of Ti6Al4V alloy with bioglass and corrosion protection by silane coating
(CDRR Editor) Marcolin, Patricia; Frozza, Caroline Olivieri da Silva; Henriques, João Antonio Pêgas; Kunst, Sandra Raquel; Crovace, Murilo Camuri; Ely, Mariana Roesch; Vieira, Lucia; Farias, María Cristina Moré; Brandalise, Rosmary Nichele
The Ti6Al4V alloy is usually employed as a biomaterial, however, when in use, exhibits a few drawbacks such as corrosion, caused by the release of aluminum and vanadium ions besides the bioinert behavior. Bioactive coatings offer a barrier effect and bioactivity, promoting biocompatibility and osseointegration processes. The present work aims to study the biocompatibility behavior of a bioglass-containing silane film deposited on a titanium alloy (Ti6Al4V) substrate. The effect of the surface roughness of the metallic substrate was also evaluated. Film/substrate systems were characterized as their morphological, chemical, physical, electrochemical behavior, and cell cytotoxicity and cell viability. The main results pointed out that silane films augment corrosion resistance of titanium alloy substrates. The biological results indicated a growth of osteoblast cells (MG-63), for all the test conditions. The bioglass film deposited on the ground substrate exhibits the highest cell density.
Apatite‐like forming ability, porosity, and bond strength of calcium aluminate cement with chitosan, zirconium oxide, and hydroxyapatite additives
(Wiley) Saltareli, Fernanda Mara; Leoni, Graziela Bianchi; Aguiar, Nayara de Lima Ferraz; Faria, Natália Spadini de; Oliveira, Ivone Regina de; Bachmann, Luciano; Raucci Neto, Walter
This study evaluated the effect of chitosan, zirconium oxide, and hydroxyapatite on the apatite-like forming ability, porosity, and bond-strength of calcium-aluminate cements (C). Three hundred bovine root-slices were assigned to one of five groups, according to the material: MTA, C, C + chitosan (Cchi), C + zirconium oxide (Czio),and C + hydroxyapatite (Chap), and within each group, two subgroups, according to the immersion: deionized water or phosphate-buffered saline (PBS) up to 14 days.Assessments (n = 10) of apatite-like forming ability were performed using scanning-electron microscopy, energy-dispersive x-ray spectroscopy, Fourier-transform infra-red spectroscopy, and x-ray diffraction. PBS was evaluated for pH and Ca 2+ release(n = 10). Bond-strength was analyzed by push-out test (n = 10) and porosity bymicro-CT (n = 10). Chemical and push-out data were analyzed by ANOVA and Tukey's tests (α = .05). Porosity data were analyzed by the Kruskal-Wallis and SNK tests (α = .05). Similar Ca/P ratios were observed between all groups (p > .05). The pH of MTA and Cchi were higher than that of other cements at d 3 and 6 (p < .05).Cchi had a higher release of Ca 2+ up to 6 days (p < .05). All cements had lower poros-ity after PBS (p < .05). Cchi and Chap had similar porosity reduction (p > .05), and were higher than MTA, C, and Czio (p < .05). Cchi had higher bond-strength than the other groups (p < .05). PBS samples had higher bond-strength (p < .05). All cements had hydroxyapatite deposition and the chitosan blend had the lowest porosity and the highest bond-strength
Application of mid-infrared vibrational spectroscopy with Fourier transform (FTIR) in quality evaluation in commercial coffees
(CDRR Editors) Fontes, Vitória; Pereira, Douglas Cubas; Lyra, Lucas Ferreira; Sakane, Kumiko Koibuchi
Currently, Brazil is the largest exporter and producer of coffee in the world, and it is the second most consumed beverage in the world, only behind water. In the years 2019 and 2020 it is estimated that the world consumption of coffee was 168.84 million bags of 60 kg, Brazil consumed 20 million bags of coffee, the second-largest consumer in the world, only behind the United States with 25 million bags. The techniques such as infrared spectroscopy has been applied in the food industry, as it is a fast, easy technique, without the need for reagents, free from polluting processes, and capable of analyzing the simultaneous composition of the constituents. The present study aims to analyze the changes in the chemical constituents of Brazilian commercial coffees as a function of shelf life through Fourier transformed infrared spectroscopy (FT-IR) associated with chemometric methods. The experiments were carried out within the expiration date, 6 months, and a year after the expiration date. Spectra were obtained in the range from 4000 to 500 cm-1. The studies of Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were made as discrimination methods. The areas in the region from 2970 to 2830 cm-1 and 1765 to 1720 cm-1 were calculated to analyze the alteration as a function over time. The results suggest that these bands in coffee are sensitive over time and to the storage conditions, promoting changes in aroma and flavor.

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