Biopolymers, such as Polyhydroxybutyrate (PHB), present sustainable alternatives to conventional petroleum-based plastics, contributing to the development of environmentally friendly materials. However, their intrinsic properties often require enhancement for broader applications. Plasma technology emerges as a promising and versatile tool to modify the physicochemical characteristics of biopolymers. In this study, the effects of indirect air plasma treatment on PHB were evaluated. PHB granules dispersed in water were treated using a plasma pen for either 40 minutes (PHB-T40) or 60 minutes (PHB-T60). X-ray diffraction (XRD) analysis revealed that plasma treatment increased PHB crystallinity, with crystallinity values rising from 40.13% in untreated samples (PHB-NT) to 41.10% and 42.13% for PHB-T40 and PHB-T60, respectively. Chain reorientation was evidenced, along with changes in lattice parameters: an increase of 1.75% in 'a', 1.54% in 'b', and a decrease of 3.28% in 'c'. Scanning Electron Microscopy (SEM) showed reduced agglomerate size, while XRD indicated increases in crystallite size by 18.73% (PHB-T40) and 13.71% (PHB-T60). Thermal analyses further corroborated these findings.

Objective: To compare the effect of applying silane prior to the adhesive with an adhesive containing silane in its composition in the cementation of fiber posts to conventional resin cement. Materials and Methods: In total 20 fiber posts were divided into two groups: silane/adhesive (G1): application of silane, followed by the application of the adhesive; and adhesive with silane (G2): application of adhesive containing silane in its composition. The test specimens were obtained from cylinders of AllCem Core resin cement, with the fiber postpositioned in the center of its long axis. The post/cement assembly was sectioned, and evaluated for bond strength (BS) by pushout test, and fracture pattern was analyzed with a stereoscopic microscope. Results: No significant difference in BS was observed between G1 (silane + adhesive) and G2 (adhesive containing silane). For fracture patterns, Type 3 (cohesive post and cement) was the most observed. Conclusions: The use of an adhesive containing silane, as per the adopted protocol, did not compromise BS when fiber posts were cemented with Allcem CORE cement. Both techniques exhibited similar results, with minor differences in fracture patterns.

Biodegradable films based on biomaterials have gained significant attention as sustainable alternatives to conventional plastic packaging, offering reduced environmental impact and potential for functional tailoring. In this study, starch films were reinforced with lignin, both untreated and modified by low-temperature plasma treatment, and analyzed after storage periods of 30 days and 2 years. The effects of lignin concentration, plasma surface modification, and sample aging were investigated through Fourier Transform Infrared Spectroscopy (FTIR) and multivariate Principal Component Analysis (PCA). Spectral data revealed variations in band intensities and shifts, particularly in regions associated with hydroxyl, methylene, and glycosidic linkages, indicating structural reorganization. PCA enabled the discrimination of samples based on lignin content, plasma treatment, and aging status, highlighting specific spectral features responsible for the observed differences. The findings demonstrate that plasma-modified lignin can alter molecular organization and long-term properties of starch films, offering a promising strategy for tuning the physicochemical behavior of biopolymeric materials.

This study evaluated the impact of using calcium hydroxide or antioxidant agents on the bond strength of adhesive restorations to bleached dentin. A total of 40 teeth were prepared and allocated into eight groups, first divided according to the surface treatment after bleaching (no treatment or application of calcium hydroxide, 10% sodium ascorbate, or 5% sodium thiosulfate for 10 minutes) and then according to the time of final restoration after treatment (immediate or after 7 days). Sodium perborate with 20% hydrogen peroxide was applied for 3 weeks using a developed artificial pulp chamber, with peroxide replacements provided every week. Composite resin restoration was performed, followed by a microtensile test. Then, specimens were analyzed using a stereomicroscope and scanning electron microscopy (SEM). Data were submitted to Kruskal-Wallis and Dunn tests (P < .05). The bond strength of nonbleached teeth was similar to the groups restored after 7 days of bleaching (P < .05). The lowest bond strength values were seen in groups restored immediately after bleaching (P < .05). In all groups, there was a considerable predominance of adhesive fractures. Delaying the final restoration of teeth submitted to nonvital bleaching by 7 days increased the bond strength. The immediate restoration of bleached teeth after using 10% sodium ascorbate or 5% sodium thiosulfate for 10 minutes showed unsatisfactory results. Irrespective of the dentin protocol applied before adhesion, bond strength values will be satisfactory when delaying the final restoration and unsatisfactory when immediately performing the final restoration. Therefore, after nonvital tooth bleaching, clinicians should always delay the final restoration for a minimum period of 7 days.

The growing interest in sustainable agricultural practices has driven the development of biopesticides, particularly those formulated with chitosan, cellulose, and essential oils. Chitosan, derived from chitin, is biodegradable and exhibits antibacterial and antifungal properties, proving effective in combating plant pathogens. Cellulose, due to its abundance and low environmental impact, is widely used in the formation of hydrogels and controlled nutrient release. Eugenol, extracted from clove oil, is known for its antimicrobial and nematicidal actions, although its application is limited by volatility and physicochemical instability. Encapsulation in Pickering emulsions, stabilized by solid particles, offers a solution to enhance the stability and efficiency of bioactive compound release. This technique presents itself as a viable alternative to synthetic pesticides, promoting more sustainable pest and disease management in agriculture. The combination of biopolymers and Pickering emulsions can lead to safer agricultural practices, reducing environmental impacts and improving pest control efficiency.

Flax fibers have attracted growing interest in the automotive industry as an eco-friendly reinforcement for polymer composites. However, their limited interfacial compatibility with hydrophobic matrices is detrimental to adhesion, a key factor in the composite mechanical behavior. To address this issue, this study investigates the surface modification of flax fibers using sulfur hexafluoride (SF6) plasma. The proposed treatment promotes fiber surface hydrophobization while preserving their bulk properties. The effect of SF6 plasma treatments on flax fiber adhesion to polypropylene (PP) blends containing post-consumer material is thoroughly examined. The analysis, conducted using scanning electron microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and infrared spectroscopy, reveals that the plasma treatment induces the etching of amorphous substances present in the fibers, including amorphous cellulose, hemicelluloses, and lignin. Plasma etching in combination with fluorination significantly enhances the adhesion of flax fibers to the PP blend matrix. Notably, the treated fibers exhibit improvements in tensile strength (9

Aiming to enhance the potential applications of bioproducts, we developed an innovative approach for their hydrophobization using plasma activation of liquids. In this study, microparticles of vegetable ivory, a porous hygroscopic material, were treated by an air plasma jet while immersed in silicone oil. The in‐liquid plasma treatment formed coatings that reduced particle water vapor sorption. Pore surface coverage and sorption reduction were enhanced by mixing silicone oil with copaiba oil‐resin ( Copaifera spp.). Mulateiro extract ( Calycophyllum spruceanum ) was not as effective, owing to a lower affinity with silicone oil. For the first time, we demonstrate the plasma‐induced coating formation on particles immersed in liquid mixtures, a process in which liquid–liquid interfacial properties play a fundamental role.

Wet beneficiation is a primary process employed by mining companies for iron ore concentration. The moisture content in the ore is a result of this beneficiation process, in addition to inherent moisture within the mineral composition. The moisture content of iron ore is a crucial parameter that requires effective control to ensure safe handling and transportation operations. Surface plasma treatment of iron ore has been investigated as a method to enhance the hydrophobicity of ore particles, thereby reducing residual moisture and water reabsorption by the particles. The samples underwent treatment using argon plasma and cold hexamethyldisiloxane (HMDSO) plasma, leading to the formation of a thin, silicon-rich surface layer. The treatments were applied to both polished ore samples and fine powder samples. The plasma treatment resulted in a reduction in moisture content and water absorption. The reabsorption of water decreased to approximately 35% of the pretreatment values. Contact angle measurements demonstrated that all HMDSO-treated samples exhibited hydrophobic behavior, with contact angles ranging from 110 degrees to 120 degrees, while the untreated samples exhibited angles close to 0 degrees. Furthermore, atomic force microscopy (AFM) topographic imaging revealed a granular structure in the thin films.

Thermoplastic starch (TPS) films underwent casting and plasma coating with Hexamethyldisiloxane (HMDSO) gas at various self‐bias voltages. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging revealed slight swelling and grain structures in untreated TPS films due to starch dissolution. However, the HMDSO plasma treatment had minimal impact, with swollen grains still present beneath a layer of small granules. Contact angle measurements demonstrated that untreated films had an initial water contact angle of 32°, gradually decreasing over time. Conversely, HMDSO‐coated films exhibited stable hydrophobic behavior, with contact angles exceeding 100°. Statistical analysis confirmed TPS films’ lower average roughness, while modified films showed no significant difference in height parameters. Higher self‐bias voltages correlated with larger grain sizes. Notably, experimental treatments decreased long‐range spatial correlations, as indicated by Hurst's exponent.

It is essential to understand the formation of the interface and the morphological design of the surface of electrodes and devices to control the structure and adapt the material to different applications. To study the interface, thin films of a PPy/[Sn(dmit)3]2 were electrochemically grown with the aid of a microcell typically used in scanning tunneling microscopy assays. Raman and FTIR spectroscopies showed the effect of dimensionality on those materials, especially on the vibrational modes of dmit ring and on the 75 nm thick PPy/[Sn (dmit)3]2 film, which presents an optimized polymer chain conjunction length and a 20 % greater contribution to the polaron charge carriers. X-ray Photoelectron Spectroscopy (XPS) analyses confirmed the polaron/bipolaron ratio data, allowing us to determine other contributions to the surface charge density. Atomic Force Microscopy (AFM) images show the hybrid thin film's different growth modes and the roughness evolution as a function of the electrochemical signal used in the synthesis.

In this work, a new approach to the synthesis of lignin-derived nanocarbon crystals based on lignin depolymerization is proposed. The lignin chemical structure was modified through a controlled routine, which was based on sequential UV light irradiation, hydrothermal carbonization in autoclave, vacuum degassing, pyrolysis and mechanical exfoliation. In this way, we were able to obtain a lignin-based nanocarbon with a sp2-hybridized nanoporous framework structure with oxygenated functional groups attached to this structure. The used catalyst-free route resulted in high nanocarbon yields and turns out to be an eco-friendly strategy of a synthesis of low-cost carbon materials. The characterization of the lignin-derived nanocarbon was carried out using X-ray diffraction measurements, infrared, Raman and X-ray photoelectrons spectroscopies analyses. The nanocarbon materials' morphology was evaluated by scanning and transmission electron microscopy. The method of lignin's transformation developed in this work showed itself as a promising alternative for provision of large amounts of carbon-based materials for industrial applications. The proposed approach may be adapted to various biomass feedstocks with aromatic groups' content suitable for their high yield polycondensation. The achieved nanocarbon yield, when starting from a commercial purified lignin, varied between 50 wt% and 70 wt%.

Natural polysaccharides, e.g., starch, cellulose and sodium alginate have been highlighted as unconventional chromophores owing to their chain structures containing clustered electron-rich groups and the rigidification imposed by inter/intramolecular interactions. On account of the abundant hydroxyl groups and dense packing of low-substituted (< 5 %) mannan chains, we have investigated the laser-induced fluorescence of mannan-rich vegetable ivory seeds (Phytelephas macrocarpa), both in the native state and after thermal aging. The untreated material emitted fluorescence at 580 nm (yellow-orange) when excited at 532 nm (green). This luminescence is intrinsic to the polysaccharide matrix abundant in crystalline homomannan, as demonstrated by lignocellulosic analyses, fluorescence microscopy, NMR, Raman, FTIR and XRD. Thermal aging at 140 °C and above intensified the yellow-orange fluorescence and caused the material to fluoresce when excited by a near-infrared laser (785 nm). In view of the clustering-triggered emission mechanism, the fluorescence of the untreated material can be attributed to hydroxyl clusters and the conformational rigidification in mannan I crystals. On the other hand, thermal aging caused dehydration and oxidative degradation of mannan chains, inducing the substitution of hydroxyl groups by carbonyls. These physicochemical changes may have affected cluster formation and increased conformational rigidification, enhancing fluorescence emission.

We evaluated the effects of dentine biomodification after pre-treatment with two sulphonamide carbonic anhydrase inhibitors (CAIs) of the N-[4-sulphamoylphenethylcarbamoyl]benzenesulphonamide type, investigating matrix metalloproteases activity, resin-dentine micro tensile bond strength, dentine surface wettability, and antimicrobial activities. Ninety-five sound-extracted human molars were selected for the study. Inhibitory effects were evaluated by gelatinase and collagenase activity tests and collagen degradation FT-IR spectroscopic analysis. Pre-treatment with the two CAIs kept the micro tensile values after 12 months of storage (32.23 +/- 5.95) and cariogenic challenge (34.13 +/- 2.71) similar to the initial, pre-treatment values (33.56 +/- 4.34). A decreased Streptococcus mutans biofilm formation on dentine surfaces and antibacterial activity against planktonic bacteria were observed after CAI treatment. Dentine pre-treatment with sulphonamide CAIs maintained adhesion strength stability, allowed better dentine wettability, maintained matrix collagen, and showed anti-S. mutans activity.

The Jarzynski equality is a fundamental result from non-equilibrium statistical mechanics that provides the difference in free energy between two states from the work done on the system by processes that can be carried out far from equilibrium. We evaluate the applicability of Jarzynski equality to map the potential energy of a model graphene surface using data from simulated Friction Force Microscopy (FFM). We model the scanning process of the FFM using the Prandtl-Tomlinson model and Langevin dynamics. By varying the simulation parameters, we verify the “stick–slip” and thermolubricity friction regimes, as well as the crossover between them. We then calculate the surface potential energy using the Jarzynski equality for these regimes. A new method for properly evaluating the free energy of the cantilever is introduced. We observe that the applicability of Jarzynski's equality is linked to the friction regimes: For thermolubricity, a very accurate potential energy curve is obtained for relatively few repetitions, but for the “stick–slip” movement, it is only possible to use Jarzynski’s equation in a small fraction of the scanning distance. For the crossover regime, it is possible to obtain a relatively accurate potential energy curve for a sufficiently large number of sampling repetitions.

PURPOSE:This study evaluated the effect of coating traditional and translucent Y-TZP with an industrial nanometric colloidal silica or glaze before or after sintering on the adhesion of zirconia with various ytrria concentration.MATERIALS AND METHODS:Specimens of Y-TZP with 3% and 5% yttria were subdivided into 5 groups (n=10), according to the coating applied and moment of application (before or after Y-TZP sintering): Control (no coating), Colloidal Silica/Sintering, Sintering/Colloidal Silica, Glaze/Sintering, Sintering/ Glaze. Lithium disilicate (LD) was used as positive control. Except for Y-TZP controls, groups were conditioned with silane before cementation with a self-adhesive resin cement. After 24 hours, the shear bond strength and failure analysis were performed. Also, analysis of specimens' surface was accomplished with SEM-EDX. Kruskal-Wallis and Dunn tests were applied to analyze differences between groups (p⟨0.05).RESULTS:Overall, the worst and best values of shear bond strength test were control and glaze after sintering groups. Different morphological and chemical aspects were observed in SEM-EDX analysis.CONCLUSIONS:Coating Y-TZP with colloidal silica showed unsatisfactory results. In 3Y-TZP, the surface treatment associated with the best adhesion values was the application of glaze after zirconia sintering. However, in 5Y-TZP, glaze application can be performed before or after the zirconia sintering to optimize clinical steps.

Anais do Simpósio de Engenharia Metalúrgica e de Materiais Sul Fluminense (978-85-5722-634-0) - Síntese, Caracterização Por Microscopia Eletrônica E Modelagem De Nano-Pós De Ha E Brushita Obtidas A Partir De Recursos Renováveis

This study evaluates the effect of two in-office bleaching agents with different compositions on the bond strength to enamel surface. Fifty bovine teeth were divided into five groups (n = 10 teeth per group), according to the bleaching agent used and the time elapsed to perform the restorative procedures: restorative procedures performed without bleaching (control group); bleaching with 35% hydrogen peroxide (HP), with restorative procedures 24 hours or 7 days after bleaching (HP/24h and HP/7d groups, respectively); and bleaching with 35% HP with calcium compost, with restorative procedures 24 hours or 7 days after bleaching (HP AutoMixx/24h and HP AutoMixx/7d groups, respectively). The specimens were stored at 37°C in artificial saliva. Restored teeth were submitted to a micro-shear bond strength test. The specimens were analyzed using a stereoscope to determine the fracture pattern, classified as adhesive, cohesive, or mixed. The results of the bond strength test were evaluated by analysis of variance, with significance set at P < .05. The groups showed similar bond strength values without significant difference among them (P > .05). There was a predominance of the adhesive-type fracture pattern in all groups. The bleaching agents with different compositions showed similar bond strength values when the restoration was performed 24 hours and 7 days after bleaching, and the results were similar to the control group.