Search Results (1,137)

This study assessed the bleaching and abrasiveness levels of different kinds of toothpaste with various RDA values on nanohybrid and microhybrid composite samples using a novel Press-on Force-Guided brushing simulator. One hundred and forty disc-shaped samples were prepared using two nano-hybrid and three microhybrid composites and divided randomly into four subgroups (n = 7). The samples were immersed in a coffee solution for 144 h and then brushed using R.O.C.S. (Remineralizing Oral Care Systems) brand toothpaste with different RDA values [Sensitive Instant Relief (SIR), Sensation Whitening (SW), and their combination with PRO Polishing (PP) (once a week)] using a brushing simulator for 140, 280 and 560 strokes (140 strokes correspondence to one week of real-time brushing). The level of surface roughness and color change (ΔE) were measured before and after the simulated brushing. Color changes were evaluated in Photoshop CC software through ∆E₀₀* values generated from before and after L, a*, b* parameters on sample photographs taken by a mobile dental photography tool. The surface structure of samples was measured before and after the brushing using a profilometer. The measurements were analyzed in SPSS V23 software by Analysis of Variance and the Bonferroni Test, and the level of significance was set at <0.05. Regarding ΔE values comparisons, there were no significant differences between the toothpastes after 2 weeks of brushing. SW (2.82 ± 1.24), SIR + PP (2.78 ± 0.98), and SW + PP (2.84 ± 1.22) values were found to be similar after one month of brushing (p < 0.007). Regarding surface roughness comparisons between the toothpastes, two-week and one-month brushing values were found to be similar and statistically rougher than the initial values. Using R.O.C.S. PRO Polishing with low-abrasive toothpaste may increase the whitening effect by enhancing color recovery. Full article

Many endodontic procedures within the pediatric population are performed with patients aged 12 years and older, using intracanal irrigants to complement mechanical debridement for the removal of debris and to disinfect the root canal system. The use of antimicrobial irrigants that limit damage to the dental pulp are the goals of endodontic biomaterials research. Using an existing biorepository of dental pulp stem cells (DPSCs), Endocyn was evaluated in varying concentrations in proliferation and viability assays, and compared with positive (sodium hypochlorite or bleach) and negative (phosphate-buffered saline) controls. The DPSC viability was reduced in the range of −8.3% to −15.8%, p = 0.22 to p = 0.042, while the growth inhibition varied between −29.7% and −63%, p = 0.041 to p = 0.022. However, the RNA analysis revealed that no significant changes in biomarker mRNA expression (Nestin, NANOG, Sox2, Oct4, CD73, CD90, and CD105) were observed. These data demonstrated that all of the concentrations of Endocyn inhibited the DPSC viability and growth, although only high concentrations were statistically significant. Moreover, the administration of Endocyn did not alter the DPSC biomarker expression, which are novel and important findings not previously observed or reported that may assist with the development of clinical decision protocols and methods for the treatment of vital pulp tissue. Full article

The limited research in Utría Cove has hindered our understanding of marginal coral areas in a rapidly changing ocean. To better understand how marginal reefs could serve as coral reservoirs where local communities could actively be involved, we assessed the ecological attributes of Utría’s coral areas, documented the impact of the 2023–2024 El Niño event, and conducted a SWOT analysis to frame the restoration potential. The current state shows a reduction of 1.4 ha in La Chola reef, where the average live coral cover is 24% and algal cover is 41%. The other two coral communities assessed (Diego and Punta Diego) showed coral cover between 14% and 17%, and algal cover between 42% and 50%, respectively. No significant differences were found in structural complexity, benthic cover, and macroinvertebrates; only fish richness was significantly higher at Punta Diego. Based on previously documented higher coral cover, the three areas need interventions (i.e., active restoration), especially considering the widespread bleaching recorded (temperatures up to 31.4 °C; sustained mean temperatures of ~30 °C ± 0.43), associated with El Niño. The SWOT analysis identified four weaknesses (e.g., logistical challenges), four threats (e.g., illegal fishing), six strengths, and six opportunities that highlight the potential to engage locals in restoration by providing economic alternatives and boosting regional initiatives. Full article

This study investigated the susceptibility of nine composite resins to turmeric staining, evaluated bleaching efficacy for color recovery, and assessed surface hardness throughout these processes. Disc-shaped specimens (8 mm × 2 mm, n = 3/group) were subjected to daily 20 min turmeric solution immersion for two weeks, followed by two weeks of daily 3 h applications of 16% carbamide peroxide bleaching. Color measurements included spectrophotometric analysis for ΔE values (threshold ΔE > 3.3 for clinical significance) and VITA Classic shade assessment at baseline, post-staining, and post-bleaching intervals. Surface hardness was evaluated using a Vickers hardness tester. Results showed significant color changes in all materials except HA after turmeric exposure, with FS exhibiting the highest staining susceptibility (ΔE = 24.6 ± 2.69) and HA showing minimal change (ΔE = 1.9 ± 0.85). VITA Classic shade evaluation revealed varying patterns; some materials maintained their initial shade designation despite significant ΔE changes (FS, CM), while others showed substantial shade shifts with successful recovery post-bleaching (HA, OM). Bleaching effectiveness varied across materials, with PO, VEP, and FS demonstrating substantial recovery in ΔE values, although FS retained clinically noticeable discoloration post-bleaching (ΔE = 7.6 ± 0.89). Surface hardness analysis revealed three distinct groups: high (80–90 HV: FS, CA, VPO), intermediate (55–70 HV: VEP, OM), and low (40–47 HV: PO, AE, HA, CM). For patients with high exposure to chromogenic foods, such as turmeric, material selection requires careful consideration of staining susceptibility, with HA and OM demonstrating superior color stability and recovery characteristics in this study. Full article

Ocean acidification (OA) associated with climate change is expected to lower the ocean’s pH by 0.5 units by 2100. Whilst associated effects such as coral bleaching and shell calcification are well documented, lesser-known impacts are the ‘invisible’ effects on animal sensory systems. Olfactory disruption impacts the behaviour towards chemical cues in many marine species, including crustaceans. We examine the effects of microplastic odour and additional stressors on the European green crab C. maenas. Using uridine diphosphate (UDP) and uridine triphosphate (UTP) as a sex pheromone bouquet, glutathione (GSH) as a food cue, and polyethylene (PE) as plastic odour, cues were mixed with carboxycellulose to create slow-release gels. Crabs were exposed to gels in seawater pH values of 8.2, 7.6, and 7.2. Crabs took longer to react to all odours in reduced pH conditions (pH 8.2 to pH 7.2, p = 0.0017). At a low pH, PE-exposed crabs exhibited attraction towards microplastic odour and changed behavioural responses by burying. The study confirms low pH as disruptive to olfaction and highlights that plastic derivatives can become more bioactive at reduced pH levels, potentially increasing the threat posed by microplastic pollution. Further research is required to determine the potential long-term impacts of the combined threat of microplastics and reduced pH in the environment. Full article

Progress in the field of biodegradable materials has been significantly accelerated in recent years, driven by the search for sustainable substitutes for fossil-derived resources. This study investigates the formulation of biodegradable films composed of polyvinyl alcohol (PVA) and nanocellulose extracted from rice husk. The rice husk underwent alkaline treatment and bleaching for cellulose extraction, followed by sulfuric acid hydrolysis to obtain nanocellulose. The cellulose and nanocellulose were characterized through Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Thermogravimetric Analysis (TGA). Films of pure PVA and those reinforced with 1 wt. % of nanocellulose were prepared using the solvent casting method. The evaluations showed that the modulus of elasticity and tensile strength of the PVA/nanocellulose films were increased by 295.45% and 29.6%, respectively, compared to the pure PVA film. The PVA/nanocellulose film exhibited the lowest solubility and water vapor permeability. Optical Microscopy confirmed a flawless surface for the nanocellulose-reinforced film, while the cellulose- and rice husk-reinforced films displayed irregularities. In the biodegradability assessment, the nanocellulose-reinforced film was the only one that withstood the experimental conditions. The results highlight the effectiveness of nanocellulose in enhancing PVA properties, making these films promising for sustainable packaging applications. Full article

This study aimed to evaluate the micro-nanostructure and color changes of dental enamel after treatment with new gel formulations containing papain or bromelain. Eighty caries-free, extracted human teeth were randomly divided into two groups (n = 40) and stained by immersion in either coffee or Tedi juice for 4 h daily over five consecutive days. After staining, the samples were washed and stored in artificial saliva at 37 °C. The stained samples were then treated with four different whitening gels (GC, G1, G2, and Opalescence 15%) for 4 h daily. Following each treatment, the samples were rinsed and stored in artificial saliva. Color changes were measured using a digital spectrophotometer to assess CIEL*a*b* ΔE* and the Whiteness index (WI). The enamel micro-nanostructure was analyzed using SEM and AFM. Data were statistically analyzed using one-way ANOVA followed by Tukey’s HSD test. The results showed that gels containing papain and bromelain were more effective than the commercial gel in removing stains. SEM and AFM analysis indicated that papain was particularly effective for removing coffee stains, while bromelain was better for stains from natural juices. Healthy enamel has a Ra value of approximately 10 nm, which increases to about 40 nm after staining. Papain restored enamel roughness to approximately 8 nm for coffee stains and bromelain restored it to 11 nm for juice stains, delivering optimal results, while commercial gel ensures a roughness of about 15 nm after stain removal. CIELAB reveals notable changes in ΔE and WI after bleaching, revealing that papain gel is optimal for coffee stain removal and bromelain gel is optimal for natural juice stains. In conclusion, dental stains should be assessed by a dentist to determine the most suitable gel for achieving optimal results. Full article

Invasive alien species pose significant ecological challenges, with Tradescantia fluminensis emerging as a major threat in Europe. This study investigates the potential of repurposing biomass from this invasive plant, collected in Galicia, for use in the pulp and paper industry. Following prior research on engineered paper made from Tradescantia fluminensis, this study examines its integration with commercially bleached eucalyptus pulp in varying proportions (90%, 70%, 50%, 30%, 10%). Key structural and physical properties, including pulp drainability, grammage, thickness, specific volume, density, and permeability, were analyzed to evaluate the viability of incorporating Tradescantia fluminensis biomass into paper production. The chemical composition and internal structures were observed using SEM visualization (JEOL 6100) to provide insights into the engineered paper’s characteristics. The findings of this study suggest that blending Tradescantia fluminensis biomass with commercial pulp could provide a sustainable approach to paper manufacturing, leveraging residues from environmental cleanup efforts to reduce reliance on traditional raw materials. The best paper qualities were obtained with medium blends, ranging from 30 to 70% and 70 to 30% biomass to raw material. At these proportions, paper properties remained balanced, integrating both visual and physical characteristics. The most relevant data were observed for drainability (35–33° SR) and air resistance, which ranged from 5.57 to 7.33 s for 300 cm³ using the Gurley method. This study highlights the dual benefits of mitigating the ecological impact of invasive alien species waste while promoting sustainable practices in the paper industry. By challenging conventional norms and exploring new possibilities, it fosters the development of sustainable paper materials capable of promoting climate awareness and strengthening the connection between consumers, materials, and production processes. Full article

Almond shells (ASs) are a potential source of cellulose that could be obtained through sustainable methods for their valorisation. Biocomposites (BCs) from polyvinyl alcohol (PVA) and cellulose are interesting materials for developing sustainable packaging materials. BC based on PVA and AS cellulose were obtained by melt blending and compression moulding, by using subcritical water extraction at 160 or 180 °C, and subsequent bleaching with sodium chlorite (C) or hydrogen peroxide (P) to purify cellulose. The influence of the purification method on the properties of BC was analysed. Fibres treated with C were better dispersed in composites than those bleached with P. Residual phenolic compounds in the fibres provide the composite with ABTS∙+ scavenging capacity in line with the residual lignin content of the fibres. Both the presence of phenols and dispersed fibres reduced the film transparency, mainly in the UV range. Fibres enhanced the oxygen barrier capacity of composites, and those treated with HP also improved the water vapour barrier capacity. Fibres treated with C better promoted the increase in the elastic modulus of the composites, due to their highest crystallinity and dispersibility, while favoured the PVA crystallisation. Therefore, the obtained AS cellulose fibres could be used to obtain thermoprocessed PVA biocomposites for food packaging applications. Full article

Oil extracted from tiger nut is a good, edible source owing to its richness in unsaturated fatty acids. This study investigated the effects of the refining processes on the flavor components of crude tiger nut oil by GC-MS and focused on the thermal stability of the refined oil under high-temperature conditions. Three different refining processes were evaluated: citric acid-assisted hydration degumming, alkali deacidification and bleaching. In the present study, the neutralization refining resulted in 11.67% losses. The refined oil had higher brightness and transparency. Moreover, 109 volatiles were identified, mainly including aldehydes, alcohols, pyrazines and furans, the characteristic flavor compounds of which present a fatty, fresh and nutty flavor. Hence, the refining processes have a significant effect on the flavor components of tiger nut oil, and the accumulated information can be helpful in increasing the tiger nut oil quality to meet the market value. The results of the thermal properties indicated the significant degradation of oleic acid and linoleic acid with prolonged heating, leading to increases in the acid value by 17 times and the peroxide value by 31 times after prolonged heating at 210 °C for 10 h compared with those without heating. When the refined tiger nut oil was heated at 210 °C for 4 h, the carbonyl value (62.6 meq/kg) exceeded the recommended value, and after heating for 8 h, the total polar compound percentages (50%, the instrument limit value) also exceeded the national standard. In order to extend the cooking heating time, it is necessary to appropriately decrease the heating temperature. This study provides a scientific reference for the frying of tiger nut oil in food and the high-temperature treatment of food containing tiger nut oil. Full article

One approach to improve long-term coral restoration success utilizes naturally stress-tolerant corals from the wild. While the focus has primarily been on thermal stress, low oxygen is a growing threat to coral reefs and restoration efforts should also consider hypoxia tolerance. Here we determine if Siderastrea siderea and Agaricia tenuifolia populations from a reef with a historical record of low oxygen exhibit evidence of local adaptation to hypoxic events, compared to populations from a reference reef. We employed a laboratory-based reciprocal transplant experiment mimicking a severe 14-night hypoxic event and monitored bleaching responses, photo-physiology, metabolic rates, and survival of all four populations during, and for two weeks following the event. In both species, we found the populations from the hypoxic reef either fully persisted or recovered within 3 days of the event. In contrast, the conspecific naïve populations from the well-oxygenated reference reef experienced bleaching and death. This showcases the vulnerability of naïve corals exposed to low oxygen but also suggests that corals from the hypoxic reef locally adapted to survive severe episodic hypoxia. Other reefs with past episodic low oxygen may also be home to corals with adaptation signatures to hypoxia and may be useful for restoration efforts. Full article

This study aimed to investigate the chemical composition and bioactivities of essential oils (EOs) from five Moroccan thyme species: Thymus broussonetii subsp. broussonetii, T. maroccanus, T. willdenowii, T. zygis subsp. gracilis, and T. satureioides, collected from various geographical regions. Gas chromatography–mass spectrometry (GC-MS) identified thymol, p-cymene, borneol, γ-terpinene, carvacrol, α-pinene, and camphene as major constituents, with variations across species. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) revealed important levels of calcium (450.6–712.2 mg/kg), potassium (255.4–420.7 mg/kg), magnesium (97.3–150.7 mg/kg), and iron (1.95–15.1 mg/kg). The EOs demonstrated strong antioxidant activity in DPPH, FRAP, and β-carotene bleaching assays. Insecticidal activity against Aphis gossypii revealed the highest efficacy with T. willdenowii EO (LC₅₀ = 6.2 µL/mL), followed by T. maroccanus and T. zygis subsp. gracilis. Additionally, the EOs exhibited potent enzyme inhibitory effects at 1 mg/mL on acetylcholinesterase (83.1–96.4%), tyrosinase (77.5–89.6%), and α-glucosidase (79.4–89.5%). These findings suggest that thyme EOs, particularly from T. willdenowii, T. zygis, and T. maroccanus, are promising candidates for integrated pest management and natural enzyme inhibitors. Their potential applications in medicinal and pharmaceutical fields underscore the need for further research to optimize their use under specific conditions and dosages. Full article

Polysaccharides represent the most abundant biopolymers in agri-food wastes and thus are the most studied polymers to produce biodegradable films for use in packaging. Starch is among the major polysaccharides extracted from food and agricultural waste that have been used as precursor material for film production. Therefore, the present study aimed at producing an active film with antimicrobial properties using starch extracted from cassava waste and oil extracted from cloves. The antimicrobial activity of the produced films was tested against Staphylococcus aureus, Salmonella Typhimurium and Listeria monocytogenes. Cassava periderm and cortex were bleached with either NaClO or H₂O₂ before starch aqueous extraction. The active films’ antimicrobial effectiveness was assessed by the formation of inhibitory halos around film disc samples in an agar diffusion method. The inhibition zone diameters were statistically similar for all microorganisms, with an average diameter of 11.87 ± 1.62 mm. The films presented an average water vapor permeability of 0.14 g mm/m² h kPa, an average tensile strength of 0.17 MPa and an elongation at break of 32.90%. Based on the determined properties, the produced films were deemed adequate for use in food packaging, in which antimicrobial activity is paramount. Full article

This study investigates the sustainable use of Eucalyptus spp. bark through different chemical (hydrothermal, acid, alkaline, and bleaching) and physical (milling) pretreatments in the production of sustainable films. Valorization of agro-industrial residues and the demand for sustainable materials pose challenges for environmentally responsible solutions. Eucalyptus spp. bark, rich in cellulose, hemicellulose, and lignin, is a promising source for creating sustainable materials like films. In this study, the use of chemical and physical treatments aims to optimize biomass extraction and improve the chemical, thermal, mechanical, and optical properties of the films. The films showed an excellent light barrier capacity, with a transmittance below 1%. Crystallinity indices varied with the pretreatment: 8.15% for hydrothermal, 7.01% for alkaline, 7.63% for acid, and 10.80% for bleaching. The highest crystallinity value was obtained through bleaching, by removing amorphous components like lignin and hemicellulose. The alkaline pretreatment yielded stronger films (maximum stress of 8.8 MPa, Young’s modulus of 331.3 MPa) owing to the retained lignin and the hemicellulose reinforcing the material. This study contributes to the field of sustainable development by converting residues into valuable materials and by advancing the circular economy. The films’ specific properties make them suitable for applications like sustainable packaging, addressing environmental and industrial challenges. Full article

A composite material based on polyvinyl alcohol (PVA) and brookite-phase titanium dioxide (TiO₂) was synthesized using a straightforward method that involved combining the polymer with a sol as a filler. The composites were analyzed using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC), and mechanical testing. The effects of treating the sol with underwater discharge plasma utilizing different electrode materials on the surface morphology, mechanical properties, thermal stability, and optical (photochromic) characteristics of the composites were investigated. FTIR spectral analysis indicated the presence of a chemical bond between the polymer matrix and the filler particles, as evidenced by the appearance of new peaks in the region of 700–500 cm⁻¹. Preliminary plasma treatment was shown to enhance the thermal stability, strength, and elasticity of the PVA-based composite. These improvements resulted from the modification of the filler (sol) due to plasma activity. The resulting composites exhibited a low photocolorization rate and a high bleaching rate. Such composites represent a promising material for use as inks in 3D printing. Full article