Search Results (126)

High safety gel polymer electrolyte (GPE) is used in lithium metal solid state batteries, which has the advantages of high energy density, wide temperature range, high safety, and is considered as a subversive new generation battery technology. However, solid-state lithium batteries with multiple layers and large capacity currently have poor cycle life and a large gap between the actual output cycle capacity retention rate and the theoretical level. In this paper, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP)/polyacrylonitrile (PAN)—lithium perchlorate (LiClO₄)—lithium lanthanum zirconium tantalate (LLZTO) gel polymer electrolytes was prepared by UV curing process using a UV curing machine at a speed of 0.01 m/min for 10 s, with the temperature controlled at 30 °C and wavelength 365 nm. In order to study the performance and failure mechanism of multilayer solid state batteries, single and three layers of solid state batteries with ceramic/polymer composite gel electrolyte were assembled. The results show that the rate and cycle performance of single-layer solid state battery with gel electrolyte are better than those of three-layer solid state battery. As the number of cycles increases, the interface impedance of both single-layer and three-layer electrolyte membrane solid-state batteries shows an increasing trend. Specifically, the three-layer battery impedance increased from 17 Ω to 42 Ω after 100 cycles, while the single-layer battery showed a smaller increase, from 2.2 Ω to 4.8 Ω, indicating better interfacial stability. After 100 cycles, the interface impedance of multi-layer solid-state batteries increases by 9.61 times that of single-layer batteries. After 100 cycles, the corresponding capacity retention rates were 48.9% and 15.6%, respectively. This work provides a new strategy for large capacity solid state batteries with gel electrolyte design. Full article

Fluoride gels are widely used in dental prophylaxis due to their proven ability to prevent demineralization and promote remineralization of hard dental tissues. However, the effectiveness of fluoride release from such gels may be significantly influenced by environmental factors such as pH and the presence of calcium ions. This in vitro study aimed to evaluate how these variables affect fluoride ion release from three commercially available fluoride gels—Clarben, Flairesse, and Lunos. The gels were incubated in artificial saliva of varying pH levels (4.5, 6.0, 7.0, and 7.5) with and without the addition of calcium, as well as in other water-based media—tap water, deionized water, and 0.9% NaCl solution. Fluoride release and changes in pH were measured and statistically analyzed using a multifactorial ANOVA. The results revealed that fluoride release was highest in calcium-free environments and at neutral to slightly alkaline pH, while the presence of calcium significantly reduced fluoride availability. Among the tested products, Flairesse and Lunos exhibited sensitivity to calcium’s presence, unlike Clarben. Fluoride release was generally higher in water than in artificial saliva. Additionally, all gels induced a decrease in pH, which varied depending on the initial pH and calcium content. These findings underline the importance of environmental conditions in optimizing the clinical efficacy of fluoride gel applications. Full article

Gel electrolytes (GEs) play a pivotal role in the advancement of lithium metal batteries by offering high energy density and enhanced rate capability. Nevertheless, their real-world application is hampered by relatively low ionic conductivity and significant interfacial resistance at room temperatures. In this work, we developed a gel electrolyte membrane (GEM) by embedding Zeolitic Imidazolate Framework-8 (ZIF-8) metal–organic frameworks (MOFs) material into a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) matrix through UV curing. The composite membrane, with 4 wt% ZIF-8, exhibited an ionic conductivity of 1.17 × 10⁻³ S/cm, an electrochemical stability window of 4.7 V, and a lithium-ion transference number of 0.7. The test results indicate that the electrochemical performance of LFP//GEM//Li battery has an initial specific capacity of 168 mAh g⁻¹ at 0.1 C rate. At 1 C, the discharge capacity was 88 mAh g⁻¹, and at 2 C, it was 68 mAh g⁻¹. Enhanced ionic transport, improved electrochemical stability, and optimized lithium-ion migration collectively contributed to superior rate performance and prolonged cycle life. This study offers novel insights and methodological advances for next-generation lithium metal batteries technologies. Full article

Red mud (RM) is a strongly alkaline waste residue produced during alumina production, and its high alkali and fine particle characteristics are prone to cause soil, water, and air pollution. Phosphogypsum (PG), as a by-product of the wet process phosphoric acid industry, poses a significant risk of fluorine leaching and threatens the ecological environment and human health due to its high fluorine content and strong acidic properties. In this study, RM-based cemented paste backfill (RCPB) based on the synergistic curing of PG and ordinary Portland cement (OPC) was proposed, aiming to achieve a synergistic enhancement of the material’s mechanical properties and fluorine fixation efficacy by optimizing the slurry concentration (63–69%). Experimental results demonstrated that increasing slurry concentration significantly improved unconfined compressive strength (UCS). The 67% concentration group achieved a UCS of 3.60 MPa after 28 days, while the 63%, 65%, and 69% groups reached 2.50 MPa, 3.20 MPa, and 3.40 MPa, respectively. Fluoride leaching concentrations for all groups were below the Class I groundwater standard (≤1.0 mg/L), with the 67% concentration exhibiting the lowest leaching value (0.6076 mg/L). The dual immobilization mechanism of fluoride ions was revealed by XRD, TGA, and SEM-EDS characterization: (1) Ca²⁺ and F⁻ to generate CaF₂ precipitation; (2) hydration products (C-S-H gel and calixarenes) immobilized F⁻ by physical adsorption and chemical bonding, where the alkaline component of the RM (Na₂O) further promotes the formation of sodium hexafluoroaluminate (Na₃AlF₆) precipitation. The system pH stabilized at 9.0 ± 0.3 after 28 days, mitigating alkalinity risks. High slurry concentrations (67–69%) reduced material porosity by 40–60%, enhancing mechanical performance. It was confirmed that the synergistic effect of RM and PG in the RCPB system could effectively neutralize the alkaline environment and optimize the hydration environment, and, at the same time, form CaF₂ as well as complexes encapsulating and adsorbing fluoride ions, thus significantly reducing the risk of fluorine migration. The aim is to improve the mechanical properties of materials and the fluorine-fixing efficiency by optimizing the slurry concentration (63–69%). The results provide a theoretical basis for the efficient resource utilization of PG and RM and open up a new way for the development of environmentally friendly building materials. Full article

White spot lesions (WSLs) are early clinical stages of enamel demineralization, often related to orthodontic treatment or poor oral hygiene. The use of gels such as fluoride for topical application inhibits demineralization and promotes remineralization of dental tissues through various mechanisms. A variety of therapeutic approaches are available; however, recent research indicates that combined treatment strategies may yield superior clinical outcomes compared to monotherapy. The aim of this study was to critically compare the efficacy of combining multiple treatment techniques for WSLs compared to using these techniques alone. A systematic search was conducted in PubMed, Scopus, and Cochrane databases according to PRISMA guidelines. The PICO strategy was used to formulate the research question: Which clinical approaches combined or isolated (C) influence the treatment and prevention effectiveness (O) of white spot lesions (I) in humans (P) in the last ten years (T)? Inclusion criteria focused on clinical studies from the last ten years evaluating the combined use of at least two treatment techniques for WSL, resulting in a total of 8 randomized controlled trials selected from an initial pool of 1185 articles. Our results suggest that combined treatment strategies, including resin infiltration with fluoride varnish and ozone therapy combined with fluoride application, demonstrated enhanced efficacy in lesion masking and remineralization compared to single-treatment approaches. CPP-ACP and hydroxyapatite-based creams improved aesthetics, particularly when used alongside fluoride varnish. Our study concluded that the combination of remineralization agents like fluoride gel, infiltrative resins, and antimicrobial treatments offers superior outcomes on white spot lesion treatment than using these techniques alone. However, long-term clinical studies are needed to standardize treatment protocols and confirm durability. Full article

Solid-state electrolytes are widely expected to enhance the performance of lithium-ion batteries, providing higher energy density and improved safety. However, challenges still need to be solved in their practical application due to low ionic conductivity and high interfacial resistance at room temperature. In this study, we successfully developed a high-performance gel polymer electrolyte (GPEs) by blending poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP) and polyacrylonitrile (PAN) through UV curing, cross-linking with ethoxylated trimethylolpropane triacrylate (ETPTA), and incorporating Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO). At room temperature, the ionic conductivity of the GPEs was 2.8 × 10⁻⁴ S/cm, with a lithium-ion transference number of 0.6. Moreover, during lithium plating/stripping tests, the assembled Li/PPEL/Li symmetric cell exhibited stable cycling for up to 600 h at a current density of 0.1 mA/cm². Notably, the GPEs enabled the LiFePO₄/GPEs/Li battery to achieve excellent performance, delivering high discharge capacities at room temperature (164.3 mAh g⁻¹ at 0.1 C and 88.8 mAh g⁻¹ at 1 C), with a capacity retention of 89.4% after 200 cycles at 0.5 C. Therefore, solid-state batteries using this electrolyte exhibit excellent performance, including adequate capacity and cycling stability. Full article

Gel polymer electrolyte (GPE) with a polymer matrix swollen in liquid electrolytes offers several advantages over conventional liquid electrolytes, including no leakage, lightweight properties, and high reliability. While poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based GPEs show promise for lithium-ion batteries, their practical application is hindered by the intrinsic trade-off between ionic conductivity and mechanical robustness in conventional PVDF systems. Typical strategies relying on excessive plasticizers (e.g., ionic liquids) compromise mechanical integrity. Here, we propose a novel hot-pressing-induced recrystallization strategy to synergistically enhance both anisotropic ionic conductivity and puncture strength in PVDF-based GPE films. By blending PVDF with controlled amounts of 1-hexyl-3-methylimidazolium chloride ([HMIM]Cl), followed by solution casting and hot pressing, we achieve microstructural reorganization that dramatically improves through-thickness ion transport and mechanical performance. Crucially, hot-pressed PVDF with only 25 wt% [HMIM]Cl exhibits a 12.5-fold increase in ionic conductivity (reaching 4.7 × 10⁻⁴ S/cm) compared to its solution-cast counterparts. Remarkably, this formulation surpasses the conductivity of PVDF-HFP composites with a higher [HMIM]Cl content (35 wt%, 1.7 × 10⁻⁴ S/cm), demonstrating performance optimization of anisotropic conductivity. What is more, the mechanical strength of the piercing strength perpendicular to the GPE film after hot pressing increased by 42% compared to the solution-cast film. This work establishes a scalable processing route to break the conductivity–strength dichotomy in GPEs, offering critical insights for designing high-performance polymer electrolytes. Full article

The Hall–Héroult aluminum production process generates lithium-rich waste barrier materials, which are challenging to process using conventional acid leaching due to the environmental risks posed by hydrofluoric acid (HF) emissions. This research introduces a two-stage water–HCl sequential leaching (WHSL) approach to recover lithium while reducing these environmental impacts. The method evaluates key factors, such as the liquid–solid ratio, temperature, duration, rotation speed, and HCl concentration, and compares its efficacy with traditional HCl leaching using XRD, FTIR, DBP, and SEM techniques. The findings indicate that initial water leaching dissolves NaF salts, creating surface grooves and cracks. Subsequent HCl leaching selectively extracts lithium from aluminum and silicon, forming silica gel while preserving the nepheline phase due to its structural integrity. The process produces a porous residue with smaller particles, reduced surface potential, and promotes colloidal aggregation. This two-step process achieves efficient lithium recovery while reducing acid consumption and minimizing hydrogen fluoride (HF) emissions. Full article

Fluoride has remained the most important ingredient in the prevention of tooth decay for many years. Therefore, fluoride prophylaxis should be highly individualized to provide patients with maximum benefits while minimizing the risk of toxic effects. This study aims to compare the degree of fluoride ion release from two commercially available dental fluoride gels (Fluormex and Fluor Protector Gel) in five different physiological solutions as well as their effect on pH. The concentration of fluoride ions and pH of tap water, distilled water, demineralized water, NaCl, and artificial saliva were evaluated before and after 48 h after dissolving and incubating the same amounts of gels. The concentration of fluoride ions was higher in solutions containing Fluormex than Fluor Pro-tector Gel (p < 0.05), with the highest concentration in demineralized water (16,917 ppm). It was accompanied by a decrease in pH below the critical value of 5.5 in all solutions except tap water. Not only the composition of the gel but also the chemical composition of the environment affects the release of fluoride ions. No relationship was found between the change in pH and the concentration of fluoride ions. Full article

Combining large-sized flaky alumina and spherical alumina as thermally conductive fillers in thermal management materials can effectively establish heat-conducting pathways and significantly increase the system’s heat conduction value. Conventional preparation processes typically produce flaky alumina with a small size and a low diameter-to-thickness ratio, often failing to meet the requirements for applications as thermally conductive fillers. By combining the conventional molten salt method with gas-phase fluoride ions, this study produced large-sized, flaky α-Al₂O₃ with a diameter ranging from 10 to 50 μm, a thickness of 200–500 nm, and a diameter-to-thickness ratio between 80 and 150. This study revealed that as the size of the flaky alumina increases, so does the thermal conductivity value, but the viscosity also rises, and the limit filling rate decreases. When 3% of the large-sized flaky alumina was added to the compounded thermal conductive filler system, the thermal conductivity of the gel increased by 25%. Full article

Research with nanoparticles for the treatment and prevention of dental caries is of special interest given the high prevalence of the disease worldwide. Several studies support the use of nanoparticles associated with materials given their antimicrobial properties and potential demineralization reduction. This study aimed to evaluate the impact of the application of silver nanoparticles (AgNPs) and chitosan gel in combination with commercial fluoride varnish on the remineralization of dental enamel. Ninety-six tooth blocks were macroscopically evaluated via stereomicroscopy, ICDAS II, and laser fluorescence. Enamel blocks were subjected to artificial demineralization and divided into four exposure groups (24, 48, 120, and 168 h), and five different remineralizing agents were applied, namely, FV (fluoride varnish), FV + CG (fluoride varnish + chitosan gel), FV + AgNPs (fluoride varnish + AgNPs), FV + AgNPs + CG (fluoride varnish + AgNPs + chitosan gel), and AgNPs + CG (AgNPs + chitosan gel). Enamel surface changes were evaluated via laser fluorescence, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Laser fluorescence results obtained from demineralized blocks and subsequently exposed to remineralizing treatment indicate significant differences. After exposure to remineralizing agents, hydroxyapatite and modified apatite phases were identified mainly in the samples treated with FV + AgNPs + CG in the groups exposed for 24, 48, and 120 h. The FV + AgNPs + CG and AgNPs + CG indicate good performance in terms of the Ca/P ratio in in vitro demineralization compared to the group treated with fluorine varnish. Full article

Background: The World Health Organisation (WHO) included silver diamine fluoride (SDF) in the WHO Model List of Essential Medicines for the management of early childhood caries. SDF is typically available as a 38% aqueous solution, which is watery to apply. A 38% SDF gel has recently been developed, but its caries-arrest effectiveness remains unsubstantiated. The objective of this study is to determine whether the efficacy of a 38% SDF gel is non-inferior to a 38% SDF solution in arresting early childhood caries. Methods: This is a 30-month, randomised, active-controlled, parallel-group non-inferiority pragmatic clinical trial with two arms. The hypothesis is that the 38% SDF gel is not worse than the 38% SDF solution by a non-inferiority margin of 10% caries-arrest rate when applied semi-annually to preschool children. This trial will recruit 630 3-year-old kindergarten children through block randomisation to receive either an application of SDF gel or SDF solution on cavitated carious lesions in their primary teeth every 6 months. The primary outcome is the proportion of soft (active) carious tooth surfaces that turn hard (arrested) at the 30-month follow-up. The same calibrated dentist will conduct 6-monthly dental examinations in the kindergartens to assess the status of carious lesions over 30 months. The examiner, the children, and parents will be blinded to treatments. The parents will be surveyed on their child’s oral health-related behaviours and socioeconomic background to allow adjustment for effect modification. Results: If the anticipated results are obtained, clinicians can use the 38% SDF gel as an alternative of the 38% SDF solution in arresting early childhood caries. Conclusions: As SDF gel is cost-effective, non-invasive, and non-aerosol-generating, it can be widely recommended for caries control. Trial registration: ClinicalTrials.gov NCT06241261. Registered on 7 February 2024. Full article

Bacterial infections are a common cause of clinical complications associated with the use of orthodontic microimplants. Biofilm formation on their surfaces and subsequent infection of peri-implant tissues can result in either exfoliation or surgical removal of these medical devices. In order to improve the properties of microimplants, hybrid coatings enriched with silver nanoparticles, calcium, and phosphorus were investigated. The present study aimed to assess the microstructure of commercially available microimplants composed of a medical TiAlV (Ti6Al4V) alloy covered with organic–inorganic layers obtained by the sol–gel method using the dip-coating technique. The microstructures and elemental surface compositions of the sterile, etched, and layer-modified microimplants were characterized by scanning electron microscopy with X-ray energy-dispersive spectroscopy (SEM-EDS). Elements such as silver (Ag), calcium (Ca), phosphorus (P), silicon (Si), oxygen (O), and carbon (C) were detected on the microimplant’s surface layer. The SEM observations revealed that control microimplants (unetched) had smooth surfaces with only manufacturing-related embossing, while etching in hydrofluoric acid increased the surface roughness and introduced fluoride onto the microimplants. Layers with only silver nanoparticles reduced the roughness of the implant surface, and no extrusion was observed, while increased roughness and emerging porosity were observed when the layers were enriched with calcium and phosphorus. The highest roughness was observed in the microimplants etched with AgNPs and CaP, while the AgNPs-only layer showed a reduction in the roughness average parameter due to lower porosity. Enhancing the effectiveness of microimplants can be achieved by applying selective surface treatments to different parts. By keeping the outer tissue contact area smooth while making the bone contact area rough to promote stronger integration with bone tissue, the overall performance of the implants can be significantly improved. Full article

An intraoral fluoride-releasing device (IFRD) is a cost-effective tool for introducing fluoride into the oral cavity. It allows prolonged uptake of low concentrations of fluoride into teeth. We developed a new IFRD using 3D additive manufacturing and a new low-release fluoride gel. Gels for IFRDs were synthesized from hydroxyethyl cellulose (SE600) and cationic hydroxyethyl cellulose (L200). We compared the effects of the new cationic fluoride slow-release gel and non-cationic gel on enamel acid resistance in vitro. Cationization significantly increased fluoride ion concentration, as evident from its concentrations of 0.68 ± 0.08 ppm for SE600 and 4.24 ± 0.83 ppm for L200 after 60 min of immersion in distilled water. In addition, the acid resistance of bovine tooth enamel post-application was analyzed by measuring tooth loss, mineral loss (ΔZ), and lesion depth (Ld) using polarized light microscopy, electron microscopy, and micro-radiography. Compared to the SE600 group, the cationic L200 group had significantly reduced ΔZ and Ld, enhancing enamel acid resistance. This device could be implemented in areas where adequate oral care is challenging, including preventive dentistry, ward management, nursing homes, and dental clinic visits. Full article

Oral rehabilitation with dental implants has resulted in high success rates. However, some complications have been described, such as the loss of the prosthetic screw. Some manufacturers sell screws with different coatings to avoid screw loosening, but even these types of screws can come loose. We aimed to investigate the screw coatings that can be applied during a dental appointment to avoid screw loosening. Following PRISMA Guidelines, we searched PubMed/Medline, Embase and Web of Science for studies published up to January 2024. All studies of single dental implant crowns, in which the prosthetic screw was coated with a lubricant and the preload and/or the removal torque value (RTV) was recorded, were analyzed. We excluded studies applying the finite element method (FEM) as well as studies without a control group. The risk of bias was assessed with a tool developed by our research group. Of the 1959 records identified, 19 were selected. Ten studies were considered to have a low risk of bias, and nine were considered to have a medium risk of bias. The coatings tested were adhesives, saliva, chlorhexidine, Vaseline, silicone gel, Polytetrafluoroethylene (PTFE) tape, blood, fluoride, Listerine^® Mouthwash and normal saline. The preload, the RTV with and without cyclic loading and the percentage of RTV loss were recorded. Some coatings show promise, although there is no clear evidence that any option is superior in minimizing screw loosening. Full article