JOURNAL OF PROSTHETIC DENTISTRY
·
2023
·
IF 4.6
Yaoxin Wang,Zijing Chang,Ning Ding,Zutai Zhang
Statement of problem Secondary caries is a major factor in the failure of dental restorations . However, studies on the fabrication of acid-resistant and antibacterial dentin to improve dentin bonding are sparse. Purpose The purpose of this in vitro study was to compare the effects of 2 types of fluoride-containing etchants on dentin bonding and explore the feasibility of formulating an altered dentin substrate to improve dentin bonding. Material and methods NaF-containing and SnF 2 -containing etchants were developed by adding sodium fluoride and stannous fluoride to a 35% phosphoric acid aqueous solution. Two groups (N1 and N2) containing NaF, 10 and 30 mg/mL respectively, and 2 groups (S1 and S2) containing SnF 2, 18.6 and 55.8 mg/mL respectively, were formulated. The etchant of the control group (C) was 35% phosphoric acid gel. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), microhardness, antierosion, and antibacterial tests were performed on the treated dentin. Moreover, the microtensile bond strength (µTBS) of each group was tested, and the fracture mode was determined after testing. Statistical analysis was performed with the 2-way ANOVA test (α=.05). Results The exposed collagen fiber was observed in group C, and minerals were formed on the dentin in the experimental groups. SEM, FTIR, and the microhardness test indicated more remineralization in the SnF 2 -containing etchant groups. The µTBS of S1 (77.5 ±10.36 MPa) was the highest in all groups, and group C (38.5 ±9.01 MPa) was the lowest. Moreover, the antierosion and antibacterial properties of the S2 group were the best among all groups ( P <.05). Conclusions Compared with NaF-containing etchant, SnF 2 -containing etchant could improve the dentin substrate, increase remineralization, improve bonding strength, and enhance antibacterial ability, especially by increasing resistance to acid erosion.
研究领域:
牙科学
·
材料科学
·
生物医学工程
✓ 已验证
DOI
PubMed
高影响因子
CHINESE JOURNAL OF ANALYTICAL CHEMISTRY
·
2021
·
IF 1.134
Yong-Sheng NIU,Li-Xin SUN,Cong-Wei HU,Jin-Hao ZHOU,Qiang DOU,Qing-Nuan LI
The fluorination behavior of molybdenum (Mo) powder with NF 3 , such as temperature dependence of reactivity, reaction mechanism and kinetics were investigated on a homemade fluoride volatility process (FVP) research device. The in-situ Fourier transform infrared (FTIR) spectroscopy was applied to determine the beginning and the end of reaction. The research demonstrated that near 500 K or lower, the reaction between Mo power and NF 3 occurred, meanwhile, the temperature had an important influence on the average reaction rate and the utilization of NF 3 . When the temperature increased from 500 K to 700 K, the average rate increased from 1.04 × 10 –2 mol/h to 2.40 × 10 –2 mol/h and the utilization of NF 3 increased from 21.2% to 49.0%. The in-situ FTIR and XRD analysis assisted by thermodynamic calculation indicated that Mo power was converted to MoF 6 through an intermediate product MoF 3 : 2NF 3 (g) + 2Mo (s) = 2MoF 3 (s) + N 2 (g), then 2MoF 3 (s) + 2NF 3 (g) = 2MoF 6 (g) + N 2 (g). Based on a mathematical model with unreacted shrinking core, the calculated reaction rate constant increased from 1.77 × 10 –2 min –1 to 3.48 × 10 –2 min –1 in the temperature range of 500–700 K, and the activation energy was 10.13 kJ/mol.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2020
·
IF 8.758
Yuanqin Li,Kang Wang,Jiawei Chen,Wenguang Zhang,Xuehuan Luo,Zhangmin Hu,Qiankui Zhang,Lidan Xing,Weishan Li
High-voltage cathodes provide a promising solution to the energy density limitation of currently commercialized lithium-ion batteries, but they are unstable in electrolytes during the charge/discharge process. To address this issue, we propose a novel electrolyte additive, pentafluorophenyltriethoxysilane (TPS), which is rich in elemental F and contains elemental Si. The effectiveness of TPS has been demonstrated by cycling a representative high-voltage cathode, LiNi0.5Mn1.5O4 (LNMO), in 1.0 M LiPF6–diethyl carbonate/ethylene carbonate/ethyl methyl carbonate (2/3/5 in weight). LNMO presents an increased capacity retention from 28 to 85% after 400 cycles at 1 C by applying 1 wt % TPS. Further electrochemical measurements combined with spectroscopic characterization and theoretical calculations indicate that TPS can not only construct a robust protective cathode electrolyte interphase via its oxidation during initial lithium desertion but also scavenge the detrimental hydrogen fluoride (HF) present in the electrolyte via its strong combination with the species HF, F–, and H+, highly stabilizing LNMO during the charge/discharge process. These features of TPS provide a new solution to the obstacle in the practical application of high-voltage cathodes not limited to LNMO.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2015
·
IF 4.321
Linyu Deng,Yawei Liu,Tinglin Huang,Tian Sun
The removal of fluoride from water by induced crystallization using fluorapatite (FAP)/calcite seed crystals was investigated. Batch experiments were conducted to determine optimal operating parameters. The effect of FAP/calcite mass ratio of the seed crystals, initial seed crystal concentration, molar ratios of Ca 2+ :PO 4 3− :F − and contact time were examined. FAP/calcite with any mass ratio reduced fluoride concentrations from 9.5 mg/L (0.5 mM) to less than 1 mg/L. The use of FAP alone and calcite alone was not effective. Use of initial seed crystal concentrations greater than 4.0 g/L were correlated to residual fluoride concentrations less than 1.0 mg/L. The optimal parameters for fluoride removal were an initial seed crystal concentration of 6 g/L (FAP 4.8 g/L, calcite 1.2 g/L), Ca/P/F molar ratio of 8:4:1, and contact time of 1 h. The final pH was always close to neutral. The presence of natural organic matter (NOM) in the raw water was found to not affect fluoride removal. SEM–EDS and XRD analysis showed that fluoride removal was due to crystallization of Ca 5 (PO 4 ) 3 F on the surface of FAP. Phosphate, but not fluoride, accumulated on calcite by adsorption. The seed crystal could be regenerated easily, and used repeatedly, and used seed crystals could also be used as resources in phosphorus fertilizer production. Induced crystallization using FAP/calcite as a seed crystal is an economically and environmentally friendly process, and has the potential to remove fluoride from groundwater.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Yinghua Xu,Tingjie Ge,Hongxing Ma,Xufen Ding,Xiaoyong Zhang,Qi Liu
Hydrodefluorination (HDF) is the key step in fluoroaromatic pollutant (FAP) degradation, making the search for efficient HDF catalysts and the determination of the corresponding mechanism a matter of great importance. In this study, we developed an efficient HDF catalyst (a Rh-Pd alloy) and investigated the underlying catalytic reaction mechanism , using 4-fluorophenol (4-FP) as a model FAP. Specifically, the rapid aqueous-phase HDF of 4-FP at pH 3 was achieved on a Rh-Pd alloy-modified Ni foam electrode, which was followed by ring hydrogenation (RH) of the HDF product (phenol) to afford cyclohexanone and cyclohexanol . Inductively coupled plasma optical emission spectrometer (ICP-OES) and thermodynamic analyses showed that, in addition to those supplied by the applied current, the electrons involved in the HDF of 4-FP and the RH of phenol were largely provided by the oxidative dissolution of the Ni foam support. Hydrogenation and cyclic voltammetry experiments indicated that the HDF of 4-FP probably follows an indirect mechanism (featuring adsorbed H atoms as the direct reductant) and that the strength of 4-FP adsorption onto the surface of the catalyst significantly influences its HDF activity.
研究领域:
环境科学
·
电化学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2021
·
IF 8.742
Yu-Xi Huang,Dong-Qing Liang,Cheng-Hui Luo,Yuanyuan Zhang,Fangang Meng
Membrane scaling is a critical challenge for membrane distillation (MD), especially when treating hypersaline brines. In this study, an anti-scaling membrane was developed with a liquid-like surface coating . This fabrication approach combined electrospun polyvinylidene fluoride (PVDF) membrane with surface fluorination without the addition of nanoparticles . Two fluoro silanes with the same alkyl-chain length but different hydrolysis reaction sites were investigated as the fluorination agents. Membrane characterizations indicated that surface modification with the single hydrolysis site fluoro silane (17-FAS-S) did not change the membrane morphology or structure. On the other hand, surface modification with the triple hydrolysis site fluoro silane (17-FAS-T) generated nanoparticles on the membrane surface, resulting in increased roughness. While both the 17-FAS-S and 17-FAS-T modified membranes exhibited excellent scaling resistance in the MD scaling tests, the 17-FAS-S membrane provided a much higher vapor flux than the 17-FAS-T one. Finally, the mechanism of scaling resistance and vapor permeability provided by the liquid-like modification was discussed.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL POLLUTION
·
2023
·
IF 8.9
Jun Hu,Yifan Qiu,Bing Gu,Nv Yao,Zimo Lou,Zhuowei Cheng,Xianzhao Zhang,Jianming Yu
Zero-valent iron (Fe) is commonly employed as an additive for the mechanochemical destruction (MCD) of organic pollutants . The poly- and perfluoroalkyl substances (e.g., perfluorooctane sulfonate , PFOS) are a class of toxic environmental pollutants that are difficult to effectively degrade due to their thermodynamic and chemical stability. In this study, magnetite (Fe 3 O 4 ) was applied to improve the milling performance of Fe to PFOS and its promoting mechanisms were emphatically explored. The desulfurization rate was in ahead of the defluorination rate because the C–S bond is less stable than the C–F bonds in PFOS. Fe 3 O 4 had an excellent reinforcement effect on the milling performance of Fe, which was mainly through accelerating the electron transfer as a conductor, reacting with Fe to produce FeO, and facilitating the formation of HO ● . During the MCD of PFOS with Fe/Fe 3 O 4 as an additive, HO ● played a dominant role in the defluorination process (accounting for >67%). After the elimination of sulfonate group (−SO 3 − ), the produced radical (C 7 F 15 CF 2 ● ) continued to react through two main pathways: one was the stepwise defluorination after hydrogenation, and the other one was oxidation reaction after alcoholization to yield the corresponding aldehydes and carboxylic acids . The optimum Fe fraction (M Fe ) was 30%, and air atmosphere was more effective than oxygen and nitrogen conditions. This study helps to comprehensively understand the role of Fe 3 O 4 in defluorination and fills the gap of Fe/Fe 3 O 4 application in the MCD of PFASs.
研究领域:
环境科学
·
污染控制
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2023
·Vol. 140
·期 11
·e53628
·
IF 3
Linlin Wang,Minjie Qu,Zhipeng Wang,Honghua Wang,Jiyong Zhao,Guangyuan Zhou
Poly(arylene ether)s with different molecular weights were synthesized via a two-step nucleophilic substitution polymerization by adjusting reaction parameters based on phenolphthalein (PHT) and decafluorobiphenyl (DFBP). The chemical structures and properties were identified by Fourier transform infrared, NMR, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, dynamic thermomechanical analysis (DMA), and so forth. The number-average molecular weight (M n ) of the resulting polymers was in the range of 23.0–49.3KDa. FPAEs (polyarylether including perfluorobiphenyl structure) were demonstrated to have outstanding thermo-resistance with 5% weight loss temperature of about 482–520°C (N 2 ) and high-glass transition temperature (about 240–250°C). FPAEs can be dissolved in conventional organic solvents, possessing excellent film-forming properties. The good mechanical properties of FPAEs were confirmed by the DMA data, with Young's modulus greater than 1.0 Gpa and modulus retention rate at 230°C >67%. FPAEs also showed good hydrophobicity and low-water absorption, in particular, FPAE-1 (FPAE-1-5 were the polycondensation products of PHT and DFBP, just the polymerization conditions were slightly modified) exhibited favorable dielectric properties: at 1 MHz, the dielectric constant and dielectric loss was 2.58 and 0.0053, respectively. Thus, FPAE-1 has broad prospective applications in microelectronic devices and communication technology.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
WATER AIR AND SOIL POLLUTION
·
2025
·Vol. 236
·期 10
·1-15
·
IF 3
Sun Yongjun,Hu Zhihao,Wang Zihan,Zhang Can,Sun Wenquan
In this work, polymeric aluminum zirconium chloride (PAZC), a defluoridating flocculant, was prepared using calcium aluminate and zirconium tetrachloride as the main materials, and its defluoridation performance was evaluated. At pH 7 and PAZC dosage (Zr) of 50 mg•L −1 , the flocculation and defluorination rates of PAZC in simulated fluorinated wastewater with initial fluoride ion concentrations of 10, 8, and 5 mg•L −1 were 90.90%, 89.38%, and 92.2%, respectively, and the residual fluoride ion concentration in the solution was reduced to 0.91, 0.85, and 0.39 mg•L −1 , respectively. The degree of the effects of the same concentration of anions on the flocculation and fluoride removal performance of PAZC was in the order of SiO 3 2− >PO 4 3− >CO 3 2− >NO 3 − >Cl − >SO 4 2− . Characterization results indicated that PAZC was a polymer containing hydroxyl bonds of zirconium–aluminum metal ions, and the surface of PAZC had a tight, dense, porous nature. Under optimum flocculation conditions, the average particle size of the flocs obtained after fluoride removal by PAZC flocculation was 2.54 μm, and the flocculation mechanism was dominated by adsorption, electro-neutralization, and ion exchange when the dosage of the PAZC was 40–50 mg•L −1 and the pH was 5–7. It is proved that the composite flocculant PAZC has good application prospects and can provide guidance for the treatment of actual fluorine-containing wastewater.
研究领域:
环境科学
·
水处理技术
·
化学工程
·
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2024
·
IF 5.1
Ranran Qi,Mengli Gao,Ziwen Gan,Mingyi Liao
This study focuses on the synthesizing of liquid-terminated carboxyl fluoropolymers (LTCFs) from poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) through microwave (MW)-assisted oxidative degradation. An in-depth analysis was conducted on the preparation process, the duration of MW irradiation, and the resulting changes in LTCFs. Chemical titration and gel permeation chromatography (GPC) revealed that the MW-assisted oxidative degradation was achieved in 150–240 s, which is several orders of magnitude shorter than heat (CH) oxidative degradation. The modifications in the structure of C═C and C═O bonds within LTCFs were investigated over a time range of 0 to 900 s using Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectrophotometry (UV–vis), and 19F nuclear magnetic resonance (19F-NMR). The analysis reveals that the dehydrofluorination reaction primarily occurs on the HFP-VDF-HFP sequence, resulting in two sequence structures: C═CZaitsev and C═CHofmann. The dehydrofluorination of the P(VDF-HFP) copolymer followed Zaitsev’s rule mainly and Hofmann’s rule slightly. Furthermore, it was observed that the processes of C═C bond formation (KHF reaction) and conversion (KC–C reaction) are in competition. When H2O2 is enough, the degradation of the P(VDF-HFP) copolymer predominantly follows the KC–C reaction and partially the KHF reaction. The opposite is true for low H2O2 concentrations. To conclude, this study suggests a mechanism for the synthesis of LTCFs using MW-assisted oxidative degradation of P(VDF-HFP). Under MW, the C atom adjacent to a C═C bond readily undergoes autocatalytic KHF reactions, creating conjugated polyene sequences of certain lengths. Meanwhile, the rapid degradation of H2O2 expedites C═C oxidative breaking, producing the COOH functional groups.
研究领域:
材料科学
·
化学工程
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Water Process Engineering
·
2023
·
IF 7
Wei Zhang,Qing Long,Guifeng Li,Zigong Ning,Lu Lu
Hydrated electron reduction in an ultraviolet (UV)-sulfite system and electrochemical oxidation on a boron doped diamond (BDD) anode both are efficient processes for the degradation of perfluorooctanoic acid (PFOA). However, hydrated electron reduction has inherent deficiency in the mineralization (i.e., converting organic carbon into CO 2 ) of PFOA. Furthermore, toxic byproducts such as partially hydrodefluorinated carboxylic acids (HDCAs) and perfluorosulfonic acids (PFSAs) might give secondary pollution if the wholly hydrodefluorination of PFOA is not achieved. BDD electrochemical oxidation can obtain a high mineralization efficiency, but it leads to a low defluorination (i.e., transforming C−F bonds into F − ions) efficiency due to the generation of toxic volatile fluorinated alkanes. Herein, we report a coupled process that is hydrated electron reduction as pre-treatment and BDD electrochemical oxidation as post-treatment to achieve a complete defluorination and mineralization of PFOA, the results demonstrate that 50 mg/L PFOA can be 100 % deluorinated and mineralized under 5 h UV-sulfite reduction followed by 10 h electrochemical oxidation. This coupled process strongly inhibits the production of the toxic volatile fluorinated pollutants and quickly converts the residual toxic sulfite in UV-sulfite system to the sulfate. Mechanism investigation demonstrates that BDD oxidation is able to transform HDCAs and PFSAs formed by hydrated electron reduction to the perfluorocarboxylic acids (PFCAs) with shorter carbon chain than PFOA, which can be further defluorinated and mineralized.
研究领域:
环境科学
·
化学工程
·
水处理
·
污染物降解
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2020
·
IF 4.049
Xiaowei Sun,Wenhua Ji,Shenghuai Hou,Xiao Wang
Trifluoromethyl covalent organic framework (CF 3 -COF) is facilely synthesized at room temperature using for solid-phase microextraction (SPME). The CF 3 -COF coating displays an improved extraction performance for per- and polyfluorinated alkyl substances (PFASs) comparing to amorphous polymer coating, non-contained fluorine covalent organic framework coating and commercially available SPME coating. The fluorine affinity of trifluoromethyl in CF 3 -COF for PFASs is demonstrated using the density functional theory calculation. Following the microextraction with CF 3 -COF-coated fiber, the targeted PFASs are eluted with 1 mL acetonitrile and quantified by ultrahigh performance liquid chromatography tandem mass spectrometry. The low limits of detection are 0.1–0.7 pg g −1 for milk and 0.2–0.8 pg g −1 for milk powder, suggesting the outstanding sensitivity. The precision for the method ranges between 2.9 and 9.9%. The fiber-to-fiber repeatability is in the range of 4.2–9.5%. Under the optimum conditions, the relative recoveries are 91.0–110% with RSDs ≤ 10% for milk and 89.8–111% with RSDs ≤ 10% for milk powder.
研究领域:
分析化学
·
环境科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）