A randomized controlled clinical evaluation of desensitization efficacy of a newly developed toothpaste with highly stabilized SnF2.

PURPOSE: To assess the relief of dentin hypersensitivity of the new toothpaste with stabilized stannous fluoride (SnF2) versus a marketed standard fluoride toothpaste as a negative control and a marketed anhydrous SnF2 toothpaste as a positive control. METHODS: This was a single-centered, randomized, controlled, double blind, clinical trial. 96 participants with hypersensitivity were enrolled in this 4-week clinical study. Electrical stimulation and evaporative air tests were performed to evaluate the desensitization efficacy. Clinical assessments were made at baseline, and after 3 days, 1 week, 2 weeks and 4 weeks of twice-daily brushing. Additionally, the influence of Sn² ⁺ species on desensitization was evaluated using bovine dentin specimens treated with toothpaste. RESULTS: All 96 enrolled participants were randomized. 96 participants completed all evaluations. Participants had an average age (SD) of 47.0 (10.5) years; 45% of participants were female. Both SnF2 toothpastes showed superior desensitization efficacy compared to the negative control toothpaste, the conventional sodium monofluorophosphate (SMFP) toothpaste, after a week. The new stabilized SnF2 toothpaste demonstrated improved electrical stimulation benefits compared to the negative control toothpaste, with increases of 15.1% after 3 days, 34.2% after 1 week, 66.3% after 2 weeks, and 111.6% after 4 weeks. Additionally, it showed relative verbal evaluation scale (VES) benefits of 14.2% after 3 days, 37.6% after 1 week, 28.9% after 2 weeks, and 37.4% after 4 weeks. The stabilized SnF2 toothpaste exhibited desensitization properties comparable to those of a commercial anhydrous SnF2 toothpaste, which typically produces undesirable side effects in the mouth. Toothpastes containing 0.454 % SnF2 exhibited perfect occlusion of dentin tubules. CLINICAL SIGNIFICANCE: The stabilized 0.454% SnF2 toothpaste exhibited significantly greater dentin hypersensitivity relief within only a week and comparable property to commercial anhydrous SnF2 toothpaste.

Visible-Light-Induced Catalytic Selective Halogenation with Photocatalyst.

Halide moieties are essential structures of compounds in organic chemistry due to their popularity and wide applications in many fields such as natural compounds, agrochemicals, and pharmaceuticals. Thus, many methods have been developed to introduce halides into various organic molecules. Recently, visible-light-driven reactions have emerged as useful methods of organic synthesis. Particularly, halogenation strategies using visible light have significantly improved the reaction efficiency and reduced toxicity, as well as promoted reactions under mild conditions. In this review, we have summarized recent studies in visible-light-mediated halogenation (chlorination, bromination, and iodination) with photocatalysts.

Platinum Supported Nitrogen-Doped Carbon Nanotubes/ZIF-8 Derived Carbon Composite Electrodes for a Methanol Oxidation.

Pt-supported on ZIF-8 derived porous carbon (CZIF8) and nitrogen-doped multi-walled carbon nanotubes (NCNT) composites was prepared by pyrolysis process and chemical reduction. The electrochemical characterization and morphological analysis of composites was measured by cyclic voltammetry (CV), chronoamperometry, transmission electron microscope (TEM), and fourier transform infrared spectroscopy (FT-IR). These results indicate that the Pt-NCNT@CZIF8 nanocomposite showed electrochemically superior properties to methanol oxidation reaction and the higher electrochemical surface area (ECSA). Also, ZIF-8 derived carbon and modified the CNTs was thought to enhance the effective area of the platinum deposition site.

Facile and Low-Cost Fabrication of Cathode Protection Thin Layer for Durable Li-S Batteries.

A new and cost-efficient way of confining the diffusing polysulfides within the sulfur cathode is presented on the basis of employing a porous diatomite that is highly abundant in nature. The sulfur cathode coated with diatomite layer exhibited a significantly reduced capacity fade during the first two cycles, implying that the loss of active materials due to the migration of polysulfides can be mitigated by the protective layer. The diatomite-layered cathode demonstrated excellent cycling stability as high as 85% after 100 cycles. These results clearly indicate that the polysulfide diffusion is effectively blocked and the dissolved polysulfides are well confined within the protected cathode region.

High-Energy-Density Li-S Batteries with Additional Elemental Sulfur Coated on a Thin-Film Separator.

For the development of high-areal-capacity Li-S batteries, sulfur-coated separators were utilized between the cathode and anode. It was found that (1) the additional sulfur on the separator participated at the electrode reaction occurring in the cathode region, contributing to the improvement of the areal capacity of Li-S batteries, and (2) the areal capacity significantly increased with the mass ratio of sulfur on the separator (Ssep) to sulfur in cathode (S+). At the high Ssep/S+ mass ratio of 5.0, the Li-S cell delivered fourfold higher areal capacity of 4.28 mAh/cm² than that of the control cell, along with excellent capacity retention of 90% after 50 cycles, demonstrating that the new concept for Li-S cells could be highly advantageous in boosting the Li-S battery cell performance. The new approach can be widely applied to increase the areal capacity and volumetric energy density of Li-S batteries.

Effect of Reducing Agent on Preparation and Electroactivity of MnO2/Graphene Composite Electrode for Capacitors.

Supercapacitor electrodes materials with improved electrochemical properties were prepared by synthesizing manganese dioxide (MnO2) in an aqueous solution of graphene having a wide specific surface area and high electrical conductivity. MnO2/graphene composites were synthesized by reducing potassium permanganate with three kinds of reducing agent (ethanol, ethylene glycol, DMF). TEM-image confirmed that the MnO2/graphene composite which was reduced by ethanol had a small average particle size. Electrochemical properties were characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge test in 1 M Na2SO4 aqueous electrolyte solution. The MnO2/graphene composite reduced by ethanol showed higher specific capacitance than the MnO2/graphene composite reduced by ethylene glycol or DMF. It was concluded that the manganese dioxide reduced by ethanol having a small average particle size, resulting in a large specific surface area and low impedance characteristics.

In Situ Synthesis of Graphene Nanosheet/MoS2 Composite Electrodes and Their Electrochemical Performance for Lithium Secondary Cells.

Graphene nanosheet (GNS)/Molybdenum disulfide (MoS2)-sulfur composites were prepared by an In Situ solution-phase synthesis method. The practical implementation of lithium sulfur battery has not been realized by low discharge capacity and fast capacity decay during cycling owing to dissolution of lithium polysulfide into the electrolyte. In this work, we found that the GNS/MoS2 composites could mitigate the polysulfide dissolution and enhance the cycling stability via the MoS2 interaction. Electrochemical performances of prepared composites were evaluated in lithium batteries by galvanostatic cycling and cyclic voltammetry. When applied as the cathode in lithium sulfur batteries, GNS/MoS2 composites exhibited a high reversible capacity of 1143.4 mAh g-1 at the first cycle and maintain a satisfactory cyclability.

Preparation and Electrochemical Behaviors of Sulfur-Containing Electrodes as a Function of Thermal Treatment Temperature.

Zeolitic imidazolate framework-sulfur composites were synthesized by a simple solvothermal reaction. Furthermore, following thermal treatment enable electrochemical properties to be improved. In order to investigate optimal temperature, we conducted thermal treatment as a function of different temperature. The morphology of the composites was examined by Field Emission Scanning Electron Microscopy and Fourier Transform Infra-red Spectroscopy. Electrochemical characterizations were also conducted by cyclic voltammetry and Galvanostatic charge-discharge tests. Based on these electrochemical experiments, the sample treated at 900 °C indicated the highest initial specific capacity and retention property in this study. From the results of this study, sulfurcontaining composite treated at higher temperature showed the better characteristics of electrochemical performance.

A Novel Emulsion-Based Replica Method for the Synthesis of Mesoporous Carbon.

We present a novel approach for the synthesis of large-pore mesoporous carbon with a highly porous structure, based on an oil/water (O/W) emulsion templating method. For the formation of oil-in-water emulsions with nanoscale oil droplets, polyvinylpyrrolidone was used as an emulsifier. Mesoporous carbon materials with large mesopores were successfully synthesized via a three-step process: (1) polymerization in the oil-in-water emulsion, (2) filtration, and (3) carbonization. We confirmed that the pore size of the carbon can be significantly reduced through a modified O/W emulsion method. The mesoporous carbon materials prepared without an activation step exhibited an appreciable surface area (705 m2/g) and a noticeable capacitive performance of ∼100 F/g at 2.0 A/g. We believe that the approach presented here can be widely applied to the synthesis of mesoporous carbon using various carbon sources, and the structural properties of the mesoporous carbon can be improved through proper optimization.

Colloidal Silica Templated Mesoporous Carbons from a Maltose Solution for Use in Supercapacitor Electrodes.

A series of disordered mesoporous carbons (DMC) are synthesized via the colloidal silica template method by varying the mass ratio of silica to maltose from 0.4 to 1.4. A gradual improvement in the surface area and porosity of the DMC is apparent with an increase in the ratio of silica to maltose. The capacitance of the DMCs tends to increase linearly with their surface area. In particular, the DMC synthesized at a mass ratio of 1.4 exhibits the largest surface area of 1,152 m2/g and the highest capacitance of 175.4 F/g, comparable to the capacitance of other porous carbons with large surface areas (>2,000 m2/g). This feature may be attributed to its unique structural properties, such as the high pore interconnectivity allowing for easy access of the electrolyte ions. We believe that a higher capacitive performance can be achieved through further optimization studies (e.g., searching for better carbon precursors and adjusting the mass ratio of silica to carbon precursor).

Conducting Polymer Coated Graphene Oxide Electrode for Rechargeable Lithium-Sulfur Batteries.

Poly(diallyldimethylammonium chloride) (PDDA)/graphene oxide-sulfur composites were prepared by a chemical oxidation method. For the PDDA-GO composites, conducting polymers (PDDA) were coated on the surface of GO sheets. PDDA-GO composites could be expected to increase electrical conductivity and protect restacking of graphene sheets. And then, sulfur particles were dispersed into the PDDA-GO composites by mixing in the CS2 solvent. It is expected the PDDA-GO/S composites show the limited release of polysulfides due to the fact that it can provide high surface area, because conducting polymer can be used as spacer between graphene sheets. Electrochemical performances of prepared composites were characterized by cyclic voltammetry (CV). The PDDA-GO/S composites showed a high discharge capacity of 1102 mAh g(-1) at the first cycle and a good cycle retention of 60% after 100 cycles.

Study on ion conductivity and crystallinity of composite polymer electrolytes based on poly(ethylene oxide)/poly(acrylonitrile) containing nano-sized Al2O3 fillers.

In this paper, composite polymer electrolytes were prepared by a blend of poly(ethylene oxide) (PEO) and poly(acrylonitrile) (PAN) as a polymer matrix, ethylene carbonate as a plasticizer, LiClO4 as a salt, and by containing a different content of nano-sized Al2O3. The composite films were prepared by using the solution casting method. The crystallinity and ionic conductivity of the polymer electrolytes was investigated using X-ray diffraction (XRD) and AC impedance method, respectively. The morphology of composite polymer electrolyte film was analyzed by SEM method. From the experimental results, by increasing the Al2O3 content, the crystallinity of PEO was reduced, and the ionic conductivity was increased. In particular, by a doping of 15 wt.% Al2O3 in PEO/PAN polymer blend, the CPEs showed the superior ionic conductivity. However, when Al2O3 content exceeds 15 wt.%, the ionic conductivity was decreased. From the surface morphology, it was concluded that the ionic conductivity was decreased because the CPEs showed a heterogenous morphology due to immiscibility or aggregation of the ceramic filler within the polymer matrix.

Reduction procedure effect on the electrochemical properties of conductive carbon black supported Pt-Pd electrocatalysts.

Conductive carbon black supported Pt-Pd nanocomposites were prepared to study a difference of simultaneously and sequentially reduced Pt-Pd nanocomposites using polyol method. The concentration of Pt-Pd alloyed metals on carbon blacks (CB) was adjusted to 20 wt%. The catalysts could be characterized by transmission electron microscopy, X-ray diffraction and thermogravimetric analysis. The electrochemical activities of Pt-Pd were measured by cyclic voltammograms. As a result, electrochemical active surface area (ESA) value of sequentially deposited Pt-Pd/CB was shown to 66 m2/g, which was higher than 55 m2/g of simultaneously deposited Pt-Pd/CB. Besides, average particle size of sequentially deposited Pt-Pd/CB was calculated to 1.7 nm which was smaller than 2.2 nm of simultaneously deposited Pt-Pd/CB.

Effect of carbon black materials on the electrochemical properties of sulfur-based composite cathode for lithium-sulfur cells.

To investigate the effect of the electrode materials on the electrochemical performance of Li-S cells, sulfur cathodes were constructed using four types of carbon blacks: Ketjenblack EC-600JD (KB-600), Printex XE-2, Cabot BP-2000, and Super-P. It was found that the electrochemical performance of sulfur cathode was strongly dependent on the type of carbon black used. In the first discharge, the sulfur cathodes containing carbon blacks with a high surface area, KB-600 (SBET = 1270 m2/g), Printex XE-2 (SBET = 950 m2/g), or Cabot BP-2000 (SBET = 1487 m2/g), showed much higher discharge capacities (>1200 mA h/g) than the sulfur cathode (710 mA h/g) with Super-P (SBET = 62 m2/g). It was observed that the sulfur cathodes with KB-600, Printex XE-2, or Cabot BP-2000, which showed very similar discharge capacities one another at a low rate of 0.2 C, exhibited significantly different electrochemical behavior (the discharge capacity and midvoltage) at a high rate of 1.0 C. In particular, the sulfur cathode with KB-600 showed an extremely high capacity (831 mA h/g) with a midvoltage of 2.07 V at a 1.0 C rate, and excellent capacity retention (79%) after 50 cycles.

Volumetric analysis of cerebellum in short-track speed skating players.

The cerebellum is associated with balance control and coordination, which might be important for gliding on smooth ice at high speeds. A number of case studies have shown that cerebellar damage induces impaired balance and coordination. As a positive model, therefore, we investigated whether plastic changes in the volumes of cerebellar subregions occur in short-track speed skating players who must have extraordinary abilities of balance and coordination, using three-dimensional magnetic resonance imaging volumetry. The manual tracing was performed and the volumes of cerebellar hemisphere and vermian lobules were compared between short-track speed skating players (n=16) and matched healthy controls (n=18). We found larger right cerebellar hemisphere volume and vermian lobules VI-VII (declive, folium, and tuber) in short-track speed skating players in comparison with the matched controls. The finding suggests that the specialized abilities of balance and coordination are associated with structural plasticity of the right hemisphere of cerebellum and vermian VI-VII and these regions play an essential role in balance and coordination.

Effect of plasma treatments to graphite nanofibers supports on electrochemical behaviors of metal catalyst electrodes.

In the present work, we had studied the graphite nanofibers as catalyst supports after a plasma treatment for studying the effect of surface modification. By controlling the plasma intensity, a surface functional group concentration was changed. The nanoparticle size, loading efficiency, and catalytic activity were studied, after Pt-Ru deposition by a chemical reduction. Pt-Ru catalysts deposited on the plasma-treated GNFs showed the smaller size, 3.58 nm than the pristine GNFs. The catalyst loading contents were enhanced with plasma power and duration time increase, meaning an enhanced catalyst deposition efficiency. Accordingly, cyclic voltammetry result showed that the specific current density was increased proportionally till 200 W and then the value was decreased. Enhanced activity of 40 (mA mg(-1)-catalyst) was accomplished at 200 W and 180 sec duration time. Consequently, it was found that the improved electroactivity was originated from the change of size or morphology of catalysts by controlling the plasma intensity.

Synthesis of tin oxide nanoparticle film by cathodic electrodeposition.

Three-dimensional SnO2 nanoparticle films were deposited onto a copper substrate by cathodic electrodeposition in a nitric acid solution. A new formation mechanism for SnO2 films is proposed based on the oxidation of Sn2+ ion to Sn4+ ion by NO+ ion and the hydrolysis of Sn4+. The particle size of SnO2 was controlled by deposition potential. The SnO2 showed excellent charge capacity (729 mAh/g) at a 0.2 C rate and high rate capability (460 mAh/g) at a 5 C rate.

Synthesis and characterization of conductive core-shell polyacrylonitrile-polypyrrole nanofibers.

Nonwoven polyacrylonitrile-polypyrrole (PAN-PPy) core-shell nanofiber mats were prepared through the growth of PPy layers on electrospun PAN nanofibers via a two-step vapor-phase polymerization, i.e., the wet-coating of ferric tosylate (FeTos) oxidants on PAN nanofibers followed by exposure to pyrrole monomers in the gas phase. Under the conditions ([FeTos] = 10 wt%, reaction time = 15 min, temperature = 15 degrees C), the PPy polymerization procedure led to both a uniform coating over the PAN surface with an average thickness of 18 nm and cross-linkages among the nanofibers without a noticeable change in the highly porous nanofibrous structures. The oxidant concentration and polymerization time were found to be key parameters for achieving a good nanostructured core-shell fiber mat. FT-IR, XPS, XRD and conductivity measurements confirmed the synthesis of Tos-doped PPy with some degree of crystallinity and a high conductivity.

Development of high-energy non-aqueous lithium-sulfur batteries via redox-active interlayer strategy.

Lithium-sulfur batteries have theoretical specific energy higher than state-of-the-art lithium-ion batteries. However, from a practical perspective, these batteries exhibit poor cycle life and low energy content owing to the polysulfides shuttling during cycling. To tackle these issues, researchers proposed the use of redox-inactive protective layers between the sulfur-containing cathode and lithium metal anode. However, these interlayers provide additional weight to the cell, thus, decreasing the practical specific energy. Here, we report the development and testing of redox-active interlayers consisting of sulfur-impregnated polar ordered mesoporous silica. Differently from redox-inactive interlayers, these redox-active interlayers enable the electrochemical reactivation of the soluble polysulfides, protect the lithium metal electrode from detrimental reactions via silica-polysulfide polar-polar interactions and increase the cell capacity. Indeed, when tested in a non-aqueous Li-S coin cell configuration, the use of the interlayer enables an initial discharge capacity of about 8.5 mAh cm-2 (for a total sulfur mass loading of 10 mg cm-2) and a discharge capacity retention of about 64 % after 700 cycles at 335 mA g-1 and 25 °C.

Preparation and Electrochemical Analysis of Ni-Based Metal Organic Frameworks Containing Binary Ligands for Capacitor Electrodes.

As one of the energy storage systems, supercapacitors have quite long charge-discharge cycle life. Among many kinds of electrode materials, metal organic frameworks (MOFs) have unique properties such as high specific surface areas and large pore volume as supercapacitor electrode materials. Nickel-MOFs consist of binary ligand such as 1,3,5-Trimesic acid (H3BTC) and terephthalic acid (TPA) were used as working electrode materials in three electrode cell for capacitor system. When synthesizing MOFs, it is possible to prepare uniform crystals using hydrothermal synthesis. The morphology of composites was analyzed by field emission scanning electron microscopy (FE-SEM). Electrochemical properties were measured by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) in 6M KOH electrolyte.