Catalyzing Desolvation at Cathode-Electrolyte Interface Enabling High-Performance Magnesium-Ion Batteries.

Magnesium ion batteries (MIBs) are expected to be the promising candidates in the post-lithium-ion era with high safety, low cost and almost dendrite-free nature. However, the sluggish diffusion kinetics and strong solvation capability of the strongly polarized Mg2+ are seriously limiting the specific capacity and lifespan of MIBs. In this work, catalytic desolvation is introduced into MIBs for the first time by modifying vanadium pentoxide (V2 O5 ) with molybdenum disulfide quantum dots (MQDs), and it is demonstrated via density function theory (DFT) calculations that MQDs can effectively lower the desolvation energy barrier of Mg2+ , and therefore catalyze the dissociation of Mg2+ -1,2-Dimethoxyethane (Mg2+ -DME) bonds and release free electrolyte cations, finally contributing to a fast diffusion kinetics within the cathode. Meanwhile, the local interlayer expansion can also increase the layer spacing of V2 O5 and speed up the magnesiation/demagnesiation kinetics. Benefiting from the structural configuration, MIBs exhibit superb reversible capacity (≈300 mAh g-1 at 50 mA g-1 ) and unparalleled cycling stability (15 000 cycles at 2 A g-1 with a capacity of ≈70 mAh g-1 ). This approach based on catalytic reactions to regulate the desolvation behavior of the whole interface provides a new idea and reference for the development of high-performance MIBs.

Fluoride releasing in polymer blends of poly(ethylene oxide) and poly(methyl methacrylate).

Introduction: Polymethyl methacrylate is a polymer commonly used in clinical dentistry, including denture bases, occlusal splints and orthodontic retainers. Methods: To augment the polymethyl methacrylate-based dental appliances in counteracting dental caries, we designed a polymer blend film composed of polymethyl methacrylate and polyethylene oxide by solution casting and added sodium fluoride. Results: Polyethylene oxide facilitated the dispersion of sodium fluoride, decreased the surface average roughness, and positively influenced the hydrophilicity of the films. The blend film made of polymethyl methacrylate, polyethylene oxide and NaF with a mass ratio of 10: 1: 0.3 showed sustained release of fluoride ions and acceptable cytotoxicity. Antibacterial activity of all the films to Streptococcus mutans was negligible. Discussion: This study demonstrated that the polymer blends of polyethylene oxide and polymethyl methacrylate could realize the relatively steady release of fluoride ions with high biocompatibility. This strategy has promising potential to endow dental appliances with anti-cariogenicity.

Calcium Phosphate Ceramics and Synergistic Bioactive Agents for Osteogenesis in Implant Dentistry.

Implant-supported dental prosthetics are widely used in dental practice. Sufficient peri-implant bone tissue is a crucial prerequisite for the long-term success of this treatment, as insufficient peri-implant bone volume hampers dental implant installation and negatively influences dental implant stability. However, due to tooth extraction, bone metabolism diseases, and trauma, bone defects in the jaw are common in patients, particularly in the elderly and those suffering from underlying conditions. If this is the case, the alveolar ridge has to be augmented for reliable implant placement. Various biomaterials, growth factors (GFs) or GF-based products, and trace elements have been tested and used for alveolar ridge augmentation. Among those biomaterials, calcium phosphates (CaPs) are the most popular due to their promising biocompatibility, great osteoconductivity, and distinguishing osteogenesis. Combining CaPs with GFs or trace elements can further favor bone defect repair. This review mainly focuses on applying artificial CaP biomaterials and their combination with bioactive agents to repair bone defects in implant dentistry.

Biomimetic calcium phosphate coating on medical grade stainless steel improves surface properties and serves as a drug carrier for orthodontic applications.

OBJECTIVE: Recently, stainless steel (SSL) miniscrew implants have been used in orthodontic clinics as temporary anchorage devices. Although they have excellent physical properties, their biocompatibility is relatively poor. Previously, our group developed a two-phase biomimetic calcium phosphate (BioCaP) coating that can significantly improve the biocompatibility of medical devices. This study aimed to improve the biocompatibility of SSL by coating SSL surface with the BioCaP coating. METHODS: Titanium (Ti) discs and SSL discs (diameter: 5 mm, thickness: 1 mm) were used in this study. To form an amorphous layer, the Ti discs were immersed in a biomimetic modified Tyrode solution (BMT) for 24 h. The SSL discs were immersed in the same solution for 0 h, 12 h, 24 h, 36 h and 48 h. To form a crystalline layer, the discs were then immersed in a supersaturated calcium phosphate solution (CPS) for 48 h. The surface properties of the BioCaP coatings were analysed. In addition, bovine serum albumin (BSA) was incorporated into the crystalline layer during biomimetic mineralisation as a model protein. RESULTS: The morphology, chemical composition and drug loading capacity of the BioCaP coating on smooth SSL were confirmed. This coating improved roughness and wettability of SSL surface. In vitro, with the extension of BMT coating period, the cell seeding efficiency, cell spreading area and cell proliferation on the BioCaP coating were increased. SIGNIFICANCE: These in vitro results show that the BioCaP coating can improve surface properties of smooth medical grade SSL and serve as a carrier system for bioactive agents.

Crystalline Biomimetic Calcium Phosphate Coating on Mini-Pin Implants to Accelerate Osseointegration and Extend Drug Release Duration for an Orthodontic Application.

Miniscrew implants (MSIs) have been widely used as temporary anchorage devices in orthodontic clinics. However, one of their major limitations is the relatively high failure rate. We hypothesize that a biomimetic calcium phosphate (BioCaP) coating layer on mini-pin implants might be able to accelerate the osseointegration, and can be a carrier for biological agents. A novel mini-pin implant to mimic the MSIs was used. BioCaP (amorphous or crystalline) coatings with or without the presence of bovine serum albumin (BSA) were applied on such implants and inserted in the metaphyseal tibia in rats. The percentage of bone to implant contact (BIC) in histomorphometric analysis was used to evaluate the osteoconductivity of such implants from six different groups (n=6 rats per group): (1) no coating no BSA group, (2) no coating BSA adsorption group, (3) amorphous BioCaP coating group, (4) amorphous BioCaP coating-incorporated BSA group, (5) crystalline BioCaP coating group, and (6) crystalline BioCaP coating-incorporated BSA group. Samples were retrieved 3 days, 1 week, 2 weeks, and 4 weeks post-surgery. The results showed that the crystalline BioCaP coating served as a drug carrier with a sustained release profile. Furthermore, the significant increase in BIC occurred at week 1 in the crystalline coating group, but at week 2 or week 4 in other groups. These findings indicate that the crystalline BioCaP coating can be a promising surface modification to facilitate early osseointegration and increase the success rate of miniscrew implants in orthodontic clinics.

Degradation of tetracycline hydrochloride in aqueous via combined dielectric barrier discharge plasma and Fe-Mn doped AC.

Dielectric barrier discharge (DBD) plasma coupled with Fe-Mn doped AC (Fe-Mn/AC) was used to enhance the degradation of tetracycline hydrochloride (TCH) wastewater. Fe-Mn/AC catalysts with different Fe/Mn molar ratios were prepared by hydrothermal method, and the physical and chemical properties of the samples were explored by different characterization techniques, including XRD, SEM, TEM and XPS. The results showed that the combination of DBD with Fe2-Mn1/AC system had the highest effect, and the degradation efficiency of TCH could reach 98.8 % after 15 min treatment, which was 25.5 % higher than that of DBD-only. With the increase of discharge voltage and catalyst dosage, the degradation efficiency of TCH promoted. And initial pH had little effect on the degradation of TCH. In the combined system, the Fe2-Mn1/AC catalyst could retain an excellent stability and reusability. The addition of dimethyl sulfoxide (DMSO) showed that ·OH participated in the TCH degradation. The generated O3 might be catalyzed by Fe-Mn/AC catalyst to produce more ·OH. And more H2O2 was produced in DBD-only system than that in DBD-catalytic system. Nine main degradation intermediate products in the combined system were detected by HPLC-MS, and three possible degradation pathways were proposed.

Study on the desulfurization performance of iron/ethanolamine/deep eutectic solvent system.

Deep eutectic solvent (DES) was applied as the solvent of iron/alcohol amine system, and the prepared iron/ethanolamine/DES system was found to be a good desulfurizer for H2S removal. The absorbents were characterized by Fourier transform infrared spectroscopy. The iron/ethanolamine/DES system showed a significantly enhanced desulfurization performance compared with DES solution of iron or alcohol amine separately. Besides, the absorbents showed relatively stable desulfurization performance, which could keep a high H2S removal efficiency in a wide temperature range from 30-90°C. The iron/ethanolamine/DES system could be recycled for at least three times. The desulfurization product was analyzed by energy dispersive spectrum and X-ray diffraction, and the desulfurization product was identified as sulfur element.

Enhanced removal of hydrogen sulfide using novel nanofluid system composed of deep eutectic solvent and Cu nanoparticles.

The H2S removal performances of four deep eutectic solvent (DES) based nanofluid (NF) systems were measured using dynamic absorption experiment. The Cu containing NF system is found to be an excellent absorbent for H2S removal with a significantly enhanced desulfurization performance compared with DES original solution. Besides, the NF systems have relatively high regeneration performance. The NF systems and Cu nanoparticles before and after absorption as well as after regeneration were characterized by Fourier transform infrared (FT-IR) spectra, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscope (TEM) and energy dispersive spectrum (EDS). It is found that the ethanolamine, choline cation and sulfur were accumulated on the surface of Cu nanoparticles after absorption, and the bulk elements on the surface were identified as Cu and S after regeneration. The S-2 was existed in the form of Cu2S, and some sulfur was oxidized to zero-valent sulfur after regeneration.

Adsorption Mechanism of Hexavalent Chromium on Biochar: Kinetic, Thermodynamic, and Characterization Studies.

The adsorption mechanism of Cr6+ on biochar prepared from corn stalks (raw carbon) was studied by extracting the organic components (OC) and inorganic components (IC). Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the properties of three kinds of carbon. Kinetic and thermodynamic experiments were performed. The results showed that the experimental data were fitted well by the Freundlich model and the pseudo-second-order kinetic model, and the adsorptions on the three kinds of carbon were all spontaneous, endothermic processes. The adsorption of Cr6+ by biochar was in accordance with a chemisorption process. The adsorption contribution rate of the OC was 97%, which was much higher than that of the IC. Electrostatic attraction and redox reaction were the main mechanisms of adsorption, and among them, the contribution rate of the redox reaction accounted for 61.49%. The reduced Cr3+ could both exchange ions with K+ and dissociate into solution by electrostatic repulsion; the amount of Cr3+ released into the solution was approximately 17.07 mg/g, and the amount of Cr3+ ions exchanged with K+ was 0.29 mg/g. These results further elucidate the adsorption mechanism of Cr6+ by biochar.

Removing organic matters from reverse osmosis concentrate using advanced oxidation-biological activated carbon process combined with Fe3+/humus-reducing bacteria.

The high-concentration wastewater produced in the industrial reverse osmosis (RO) process contains a large amount of refractory organic matters, which will have serious impacts on the natural environment and human health. Among them, contaminants can be transformed by humus-reducing bacteria based on humus. In this study, O3- assisted UV-Fenton method was applied as pretreatment. Biological activated carbon (BAC) technology in which humus-reducing bacteria were the dominant bacteria, enhanced by electron donor and Fe3+, was used to dispose of RO concentrate (ROC). The results showed that water treatment process combining oxidation with biological filtration had a positive effect on the removal of stubborn contaminants in ROC. The system was strengthened by adding electron donor and Fe3+, and the chemical oxygen demand (COD) removal efficiency was up to 80.1%. However, when the removal efficiency of UV254 absorbing pollutants reached optimal value (87.3%), that means only Fe3+ was added.

Study on the Desulfurization and Regeneration Performance of Functional Deep Eutectic Solvents.

Four deep eutectic solvents (DESs) were synthesized, and 5-30% polyethylenimine (PEI) was added to make functional DESs (FDESs) for dynamic absorption experiments of hydrogen sulfide. The synthesized FDESs were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and nuclear magnetic resonance. The results demonstrated the successful synthesis of FDESs. The interaction between H2S and the FDESs was discussed at a molecular level via the quantum chemical calculations. It was noticed that FDESs prefer chemisorption on H2S. In this work, the 25% PEI/FDES@EG showed the highest desulfurization performance. The effects of H2S concentration and temperature on the desulfurization performance were investigated. It was found that a relatively low temperature (30 °C) was favorable for the absorption of H2S. The 25% PEI/FDES@EG could remove H2S efficiently over a low H2S concentration. Moisture played an important role in the FDES desulfurization system. The absorption/desorption cycle experiment indicated that the FDESs retain their good regeneration performance for at least five times.

Enhanced removal of NO3-N from water using Fe-Al modified biochar: behavior and mechanism.

To remove NO3-N from water, coconut shell biochar (CSB) was modified by a solution of FeCl3, a solution of AlCl3 and a mixture solution of FeCl3 and AlCl3 respectively. The obtained modified biochar with the best effect of NO3-N adsorption was screened out to explore the adsorption behavior and mechanism of NO3-N removal by batch experiments and kinetics and thermodynamics and correlated characterization. The results indicated that the mixture solution of FeCl3- and AlCl3- modified CSB (Fe-Al/CSB) showed the best adsorption performance for NO3-N removal. Iron and aluminum elements existed on the surface of Fe-Al/CSB in the form of FeOOH, Fe2O3, Fe2+, and Al2O3 respectively. The adsorption process could reach equilibrium in 20 min. An acidic condition was favorable for NO3-N adsorption. The presence of coexisting anions was not conducive for NO3-N adsorption. The quasi-second-order model and Freundlich model could be well fitted in the adsorption process. The maximum adsorption capacity of Fe-Al/CSB fitted by the Langmuir model could reach 34.20 mg/g. The adsorption of NO3-N by Fe-Al/CSB was an endothermic and spontaneous process. Ligand exchange and chemical redox reaction were the NO3-N adsorption mechanisms which led to NO3-N adsorption by Fe-Al/CSB.

The influence of aging on the comparative terrestrial ecotoxicity potential of copper and zinc in soils.

Metal exposure to terrestrial organism is influenced by the reactivity of the solid-phase metal pool. Aging is one of the important factors that control the reactivity of the solid-phase metal pool in soil. In this study, the selected 13 soils were collected from different locations of China, representing different soil types. The reactivity variation of spiked Cu and Zn with aging was assessed in these 13 soils, and their comparative toxicity potentials (CTPs) were also calculated. The median reactive fractions (freactive) of Cu and Zn with 95% confidence intervals were 1.6 × 10-2 (3.5 × 10-6 to 2.2 × 10-1) and 0.10 (9.1 × 10-4 to 0.44) kgreactive/kgtotal, and the median CTPs for Cu and Zn were 2.09 (8.1 × 10-4 to 2.2 × 104) and 0.85 (8.5 × 10-4 to 7.2 × 102) m3/kg day, respectively. The statistical analysis indicated that aging variability in the CTP of Cu and Zn was mainly associated with the variability in soil organic carbon and pH. These results stress the importance of dealing with aging in the calculation of CTPs for terrestrial ecotoxicity of metals.

Toxicity Assessment of Binary Metal Mixtures (Copper-Zinc) to Nitrification in Soilless Culture with the Extended Biotic Ligand Model.

Metals are always found in the environment as mixtures rather than as solitary elements. Only a limited number of studies have developed appropriate models that incorporate bioavailability to estimate the toxicity of heavy-metal mixtures. In the present study, we explored the applicability of two extended biotic ligand model (BLM) approaches-BLM-f mix and BLM-toxicity unit (TU)-to predict and interpret mixture toxicity with the assumption that interactions between metal ions obey the BLM theory. Exposure assays of single and mixed metals were performed with inoculums of an ammonia-oxidizing bacterium SD5 isolated from soil. Nitrification of the cultures was the end point used to quantify the toxic response. The results indicated that the developed BLM-f mix approach could well estimate the single toxicity of Cu2+ and Zn2+ as well as their binary mixture toxicity to nitrification with >90% of toxicity variation explained. Assuming that metal ions compete with each other for binding at a single biotic ligand, the BLM-f mix approach (root-mean-square error [RMSE] = 19.66, R 2 = 0.8879) showed better predictive power than the BLM-TU approach (RMSE = 31.12, R 2 = 0.6892). The present study supports the use of the accumulation of metal ions at the biotic ligands as predictor of toxicity of single metals and metal mixtures.

Recovery of soil nitrification after long-term zinc exposure and its co-tolerance to Cu in different soils.

Soils sampled from different locations of China were used to manipulate soil microbial diversity and to assess the effect of the diversity of the soil nitrifying community on the recovery of the soil nitrification to metal stress (zinc). Ten treatments were either or not amended with ZnCl2. Subsequently, a spike-on-spike assay was set up to test for the tolerance of soil nitrification to zinc (Zn) and copper (Cu). Initially, Zn amendment completely inhibited nitrification. After a year of Zn exposure, recovery of the potential nitrification rate in Zn-amended soils ranged from 28 to 126% of the potential nitrification rate in the corresponding Zn-nonamended soils. This recovery was strongly related to the potential nitrification rate before Zn amendment and soil pH. Increased Zn tolerance of the soil nitrification was consistently observed in response to corresponding soil contamination. Co-tolerance to Cu was obtained in all 1,000-mg kg(-1) Zn-amended soils. This tolerance was also strongly related to the potential nitrification rate before Zn amendment and soil pH. Our data indicate that inherently microbial activity can be a significant factor for the recovery of soil functioning derived from metal contamination.