Search Results (136)

Gel polymer electrolytes (GPEs) typically suffer from sluggish kinetics and interfacial instability at elevated temperatures and high voltages. Herein, 3-(trifluoromethyl)-1H-1,2,4-triazole (TTA) is employed to construct an ultrathin (~25 μm), robust, and homogeneous GPE. TTA acts as a molecular bridge, significantly improving compatibility between the PVDF-HFP (Poly(vinylidene fluoride-co-hexafluoropropylene)) matrix and LLZTO (Li_6.4La₃Zr_1.4Ta_0.6O₁₂) fillers to create continuous ion-conducting pathways. Consequently, the TTA-GPEs exhibits high ionic conductivity (0.267 mS cm⁻¹ at room temperature), low activation energy (0.181 eV), and an increased lithium-ion transference number (0.425). Advanced surface analysis reveals that TTA preferentially reacts to form a dense, gradient hierarchical interphase (solid electrolyte interphase/cathode electrolyte interphase, SEI/CEI) enriched with inorganic species (LiF, Li₃N, and Li₂S) on the inner side. This architecture suppresses parasitic reactions and lithium dendrite growth. Accordingly, NCM811(LiNi_0.8Co_0.1Mn_0.1O₂)//Li batteries with TTA-GPEs demonstrate stable cycling at 80 °C and 1C, retaining 57.68% capacity after 125 cycles—significantly outperforming benchmarks. This study offers a molecular engineering strategy to simultaneously optimize bulk transport and interfacial stability for high-energy-density solid-state batteries. Full article

Pure titanium (Ti) and its alloys are the gold standard for dental implants because a stable titanium dioxide passive film provides excellent corrosion resistance in physiological environments. In this study, we aimed to examine electrochemical interactions between Ti and cobalt–chromium–molybdenum alloy (CoCrMo), and between a novel Ti–magnesium composite (BIACOM TiMg) and CoCrMo, when immersed in everyday solutions representing beverage or oral hygiene exposure. Test solutions included Coca-Cola^®, lemon juice, Elmex^® fluoride gel, Listerine^® Cool Mint, and Sensodyne^® fluoride paste. Immersion experiments paired Ti sticks with CoCrMo sticks and, separately, BIACOM TiMg with CoCrMo sticks, with three measurements per configuration. When galvanically coupled with CoCrMo, immersion in Coca-Cola produced galvanic potential differences of ~983 mV for the BIACOM TiMg-CoCrMo couple and 830 mV for the commercially pure grade 4 (CP4) Ti-CoCrMo couple, indicating significant electrochemical instability. Both materials showed significant potential increases in Elmex fluoride gel. Listerine Cool Mint and Sensodyne fluoride exposure produced electrochemical interactions exceeding 200 mV. Significant differences in corrosion stability were observed between CP4 Ti and BIACOM TiMg. These findings indicate that material pairing and electrolyte environment significantly influence galvanic behavior, with the Ti-Mg composite showing greater susceptibility than CP4 Ti, informing dental/biomedical material selection in oral environments. Full article

Up-conversion nanoparticles (UCNPs) are materials that convert near-infrared (NIR) photons into ultraviolet (UV) or visible emissions. To enhance their optical properties, UCNPs are often synthesized with oxide (Y₂O₃) or fluoride (NaYF₄) support matrices, useful for energy storage applications. In this study, NaYF₄-UCNPs were synthesized via coprecipitation and heat-treated at 400 °C. Then, a tetraethyl orthosilicate (TEOS) film was synthesized by the sol–gel technique at varying pH and temperatures from 25 °C to 80 °C. Characterization using scanning electron microscopy (SEM), X-ray diffraction (XRD), and confocal microscopy (CM) confirmed the up-conversion properties. These materials show promise for enhancing solar radiation density in polymer degradation. Full article

This work deals with the comparative analysis of fluoride coatings, i.e., 5 wt.% AlF₃ and LiF, applied as surface layer of Li-rich Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ (LNCM) layered oxides synthesized via facile and cost-effective sol–gel route. The detailed structural and morphological characterizations demonstrate that AlF₃ and LiF deposits have a pivotal role in enhancing the electrochemical properties of LNCM. These electrochemical properties include galvanostatic charge–discharge (GCD), differential capacity (dQ/dV), electrochemical impedance spectroscopy (EIS), and area-specific impedance (ASI). A much lower decay of the discharge capacity of 0.22 and 0.25 mAh g⁻¹ per cycle was obtained for AlF₃- and LiF-coated LMNC, respectively, after 100 charge/discharge cycles at 0.1 C compared with 0.42 mAh g⁻¹ per cycle for pristine LNCM. Results evidence the non-evolution of the charge transfer resistance, enhanced lithium-ion kinetics and stabilization of electrode/electrolyte interface during cycling. Full article

Phosphogypsum-based cemented paste backfill (PCPB) represents an effective solution for managing substantial accumulations of PG. However, its practical application is limited by excessive fluoride content and insufficient strength. To systematically investigate the influence of initial fluoride content on the hydration behavior, microstructures, and strength development of PCPB specimens, synthetic phosphogypsum was prepared using CaSO₄·2H₂O and NaF to eliminate impurity interference in this study. A series of specimens was designed with varying initial fluoride content (5–70 mg/L), sand-to-cement ratios (1:6, 1:8, 1:10), and concentrations (63 wt%, 65 wt%). Setting time, unconfined compressive strength, isothermal calorimetry, X-ray diffraction, and scanning electron microscopy were employed to elucidate the effects and underlying mechanisms of fluoride on PCPB performance. The results indicate that higher initial fluoride content markedly delayed setting and reduced early strength. Calorimetric analysis confirmed that fluoride postponed the exothermic peak and extended the induction period, primarily due to the formation of the CaF₂ layer on clinker particle surfaces, which hindered nucleation and hydration. The microscopic results further revealed that high fluoride content suppressed the formation of ettringite and C-S-H gels, resulting in more porous and loosely bonded microstructures. Leaching tests indicated that fluoride immobilization in PCPB specimens occurred mainly through CaF₂ precipitation, physical encapsulation, and ion exchange. These findings provide theoretical support for the fluoride thresholds in PG below which the adverse effects on cement hydration and strength development can be minimized, contributing to the sustainable goals of waste reduction, harmless disposal, and resource recovery in the phosphate industry. Full article

In acidic environments, acid phosphatases (EC 3.1.3.2) play a crucial role in hydrolyzing phosphate ester linkages. Two isoforms of acid phosphatases, namely AP-I and AP-II, were purified to homogeneity from the seeds of Erythrina indica using a combination of gel filtration and affinity chromatography techniques. The purification process involved multiple steps to ensure the enzymes were free from other seed components, thereby facilitating detailed characterization. We report in this study the active site characterization of acid phosphatase form AP-I. The active site of purified AP-I was characterized in detail through chemical modification studies, which revealed the presence of one residue each of carboxylate, tryptophan, and serine amino acid. Substrate protection experiments using p-nitrophenyl phosphate effectively prevented the modification of all three residues, suggesting their essential role in the enzyme’s active site. These experiments provided strong evidence that these residues are directly involved in the catalytic process. Kinetic studies of the partially inactivated enzyme, achieved through the use of the specific modifying agents dicyclohexylcarbodiimide (DCCD) for carboxylate, N-bromosuccinimide (NBS) for tryptophan, and phenylmethylsulfonyl fluoride (PMSF) for serine further confirmed the involvement of these residues in the catalytic mechanism. The results demonstrated that the inactivation of any of these residues significantly impaired the enzyme’s activity, highlighting their critical roles in the catalytic process. The results provide a comprehensive understanding of the active site architecture and the catalytic mechanism of AP-I function. Full article

Fluoride prophylaxis is a cornerstone in preventing dental caries, a disease for which orthodontic patients are at high risk due to the reduced effectiveness of home oral hygiene and increased plaque accumulation. Recent evidence defines caries as polymicrobial, involving Streptococcus mutans, Lactobacilli, and emerging species such as Selenomonas sputigena. This prospective, randomized, controlled study evaluated professional topical fluoride in the form of gel and varnish in 68 patients aged 8–17 years wearing fixed orthodontic appliances. Participants were divided into three equal groups: two intervention groups and one control group. Clinical parameters (DMFT, salivary pH, PCR%) and microbiological analyses of plaque and saliva (oral Streptococci, S. mutans, S. sputigena, Lactobacilli, total bacterial count) were assessed at baseline (T0) and after 4 months (T1), following professional hygiene and fluoride application for the intervention groups. At T1, salivary pH increased in the gel group, and PCR% decreased significantly in all groups, with the most pronounced decrease observed in the varnish group. PCR analysis showed a higher rate of S. mutans and S. sputigena negativization in intervention groups. Culture-based analyses revealed reductions in oral Streptococci and Lactobacilli in intervention groups, while levels increased in controls. Overall, both clinical and microbiological variables indicated improvements in the fluoride-treated groups compared to controls, highlighting the efficacy of professional fluoride prophylaxis in orthodontic patients. Full article

Background/Objectives: The aim of this study was to evaluate the effects of sodium trimetaphosphate (TMP) and fluoride (F) on the surface free energy (SFE) of enamel coated with human salivary pellicle in vitro, both after treatment with the gels and after an erosive challenge. Methods: Bovine enamel discs (n = 10/group) were randomly allocated into seven treatment groups (gels): placebo (without any actives), low-fluoride gels (4500 ppm F—“4500F”) supplemented or not with microparticulate TMP (5%) or nanoparticulate (2.5% or 5%) TMP, 9000 ppm F (positive control), and 12,300 ppm F (acid gel, commercial control); a negative control group (i.e., untreated enamel) was included. Discs were exposed to human saliva (2 h), treated with the gels (1 min) and subjected to a 1-min acid challenge. Three probing liquids were used to assess enamel SFE. Data were submitted to two-way, repeated-measures ANOVA followed by Tukey’s test, and by Mann–Whitney’s test (p < 0.05). Results: SFE was significantly altered after exposure to saliva, changing from hydrophobic to slightly hydrophilic; gel treatment further increased enamel hydrophilicity (i.e., electron-donor properties), without significant differences among gels. After the erosive challenge, the enamel surface became significantly less hydrophilic for all groups; the highest values were observed for both gels containing nanoparticulate TMP. As for the overall SFE, the best performance was achieved by the gel containing 5% nanometric TMP. Conclusions: SFE of salivary-coated enamel was significantly influenced by the treatment gels, which promoted increases in hydrophilicity. Gels containing TMP, especially at nanoscale, promoted higher resistance to changes in hydrophilicity after an erosive challenge. Full article

Background/Objectives: This in vitro study evaluated the effects of fluoride-free toothpaste, fluoride-containing toothpaste, and a color-correcting gel on the morphology, composition, and mechanical properties of demineralized human enamel. The hypothesis was that fluoride-containing formulations would better preserve enamel integrity compared to non-fluoride and cosmetic products. Methods: Extracted human teeth (n = 3 per group) were demineralized with 36% phosphoric acid and assigned to four groups: E0 (control), E1 (fluoride-free toothpaste), E2 (fluoride-containing toothpaste), and E3 (color-correcting gel). Brushing was performed manually twice daily for 7 days using standardized force. Surface morphology and elemental composition were assessed via SEM–EDX; chemical changes were analyzed by FTIR; mechanical properties were evaluated using the Vickers microhardness test. Results: E1 exhibited the highest microhardness (343.6 HV) but also the highest Ca/P ratio (2.37) and most pronounced surface roughness (p < 0.05 vs. control). E2 showed a balanced Ca/P ratio (2.07), smoother morphology, and detectable fluoride incorporation, despite a lower hardness value (214.5 HV). E3 presented moderate changes in both morphology and composition, with a Ca/P ratio similar to the control (2.06) but surface irregularities visible by SEM. The apparent paradox in E1—high hardness with structural damage—may be due to superficial mineral precipitation without true remineralization. Conclusions: Fluoride-containing toothpaste preserved enamel morphology and chemistry more effectively than the other formulations. Increased hardness in E1 does not necessarily indicate clinical benefit. In vivo studies with longer protocols and pH cycling are needed to confirm these findings. Full article

Tooth whitening is increasingly sought in both clinical and home settings, raising concerns about the efficacy and safety of various whitening agents and their delivery systems. This narrative review compares the whitening performance and biocompatibility of active ingredients, including hydrogen peroxide, carbamide peroxide, activated charcoal, sodium bicarbonate, fluoride compounds, and blue covarine, with particular emphasis on the role of polymer-based carriers in formulation strategies. Hydrogen peroxide and carbamide peroxide remain the most effective agents for intrinsic whitening, but are associated with risks of enamel surface alterations, microhardness reduction, and potential cytotoxicity, particularly at higher concentrations. Sodium bicarbonate provides moderate whitening effects through extrinsic stain removal, while fluoride compounds play a supportive role by reducing demineralization and tooth sensitivity, thereby preserving enamel integrity. These properties make them valuable adjuncts or alternatives for patients with high sensitivity risks. Blue covarine offers immediate optical effects without inducing intrinsic color changes, whereas activated charcoal poses risks of enamel abrasion and surface roughness with limited long-term efficacy. Polymer-based carriers such as Carbopol gels, polyvinylpyrrolidone, and hydroxypropyl methylcellulose are incorporated into whitening formulations to improve viscosity, adhesion, and modulate the release of active ingredients. These polymers might help minimize diffusion of bleaching agents into deeper dental tissues, potentially reducing cytotoxic effects, and may improve handling characteristics. However, dedicated studies evaluating the unique advantages of polymers in different whitening systems remain limited. A comprehensive understanding of both the active ingredients and delivery technologies is critical to balancing esthetic outcomes with long-term oral health. From a clinical perspective, polymer-based carriers might contribute to reducing whitening-related tooth sensitivity, improving patient comfort, and providing more predictable treatment outcomes. Continued research is needed to clarify optimal formulations and application protocols, ensuring safer and more effective tooth-whitening practices in both clinical and home-use scenarios. Full article

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