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.

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.

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.

Three-dimensional structure analysis of mouse nails using synchrotron radiation.

Until now, studies on nail diseases have been performed through microscopic diagnosis and microscopic computed tomography (micro-CT). However, these kinds of conventional methods have some limitations. Firstly, the microscopic method is considered the gold standard for medical diagnosis. However, due to the use of fluorescent materials, the sample is damaged and it takes a long time to get results. Secondly, while micro-CT is a noninvasive method to get inner structure images of the sample with high resolution, the penetration and spatial resolution are insufficient for studying the microstructures of the sample, such as the sponge bone and the muscle fibers. In contrast, synchrotron radiation (SR) X-ray imaging technology has the advantage of very vividly demonstrating the anatomic structure of the sample with high penetration, sensitivity and resolution. In this study, we compared the optical microscopic method using hematoxylin and eosin staining and SR imaging to analyze the nail tissue in a mouse model. The results showed that SR could depict the inner structures of a mouse nail without any physical damage. Additionally, we could divide the important anatomical structures of the nail unit into three parts with three-dimensional (3D) images: the nail bed, nail matrix and hyponychium. The images showed that SR could be used for analyzing nails by visualizing the relatively clear and medically semantic structures in a 3D section. We expect that the results of this study will be applied to study nail diseases and conduct pharmaceutical research on their treatment.

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.

Three-Layer Sulfur Cathode with a Conductive Material-Free Middle Layer.

An ingenious design for a three-layer sulfur cathode is demonstrated, in which the pure sulfur layer is sandwiched between carbon nanotube (CNT) films. The unique feature of this particular model is that the sulfur layer does not contain any conductive materials, and therefore, the top CNT film of the prepared three-layer CNT/S/CNT electrode is electrically isolated from the bottom CNT film. Scanning electron microscopy studies revealed that the three-layer cathode was transformed into a single CNT cathode, with proximate contact between the two CNT films in the upper plateau of the first discharge. The lithium-sulfur cells employing a CNT/S/CNT cathode exhibited remarkably enhanced performance in terms of the specific capacity, rate property, and cycling stability compared to the cells with a sulfur-coated CNT cathode. This can mainly be attributed to the top CNT film, which serves not only as an interlayer to trap the migrating polysulfides, but also as an electrode to facilitate the redox reaction of active materials. Such an innovative approach is promising as it may promote the rational design of high-performance sulfur cathodes.

A Sulfur-Infused Separator for Boosting Areal Capacity of Li-S Batteries.

This study presents a new approach for enabling the development of high-performance lithium-sulfur (Li-S) cells by simply inserting a sulfur-infused separator (SIS) between a common S cathode and a Li metal anode. All solid sulfur electrically isolated from the cathode is electrochemically reduced to polysulfides during the first discharge. Notably, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) studies have demonstrated that the S in the separator disappears completely even when the cell is discharged to 2.1 V in the first cycle. The combination of a SIS with a typical S cathode results in the doubling of the areal capacity with superior cycling stability upon comparison with the control cell. This result demonstrates that the introduction of additional active materials, such as elemental sulfur, to a separator is a highly effective method for the fabrication of Li-S cells with a high areal capacity.

Carbon Nanotube-Based Sulfur Cathode with a Mesoporous Carbon-Silica Composite for Long Cycle Life Li-S Batteries.

The use of carbon nanotube (CNT) films as a sulfur host is a promising approach to improve the sulfur loading and energy density of Li-S batteries. However, the inability to durably incorporate polysulfides within the cathode structure results in a limited cycle life. Herein, we propose a CNTbased sulfur cathode with carbon-coated ordered mesoporous silica (c-OMS) to overcome the cycle performance issue. Scanning electron microscopy and X-ray diffraction studies on the c-OMS prepared in this work revealed that the wall surface of OMS was evenly coated with an extremely thin carbon layer. The sulfur-CNT cathode with c-OMS retained a remarkably improved capacity (942 mAh g-1) with excellent cycling stability (91%) after 100 cycles as well as significantly high sulfur utilization in the first cycle compared with the sulfur-CNT cathode with OMS. This result may stem from the surface property of c-OMS with high chemical affinity towards electrolyte solvents.

Free-Standing Sulfur-Carbon Nanotube Electrode with a Deposited Sulfur Layer for High-Energy Lithium-Sulfur Batteries.

To obtain a high S-loading cathode for a Li-S battery, we propose a free-standing carbon nanotube (CNT)-based S cathode, which consists of two layers: a pure S deposition layer with a thickness of 20 µm, and a S-containing CNT film (S-CNT). Based on scanning electron microscopic (SEM) studies, it was observed that the S layer completely vanished when the cell with the S/S-CNT cathode was discharged to 2.1 V after cell assembly, indicating that the thick sulfur film dissolved in the form of polysulfide intermediates during discharge. The proposed S/S-CNT cathode delivered double the areal capacity with good capacity retention of 83% after 100 cycles, compared with that of the control cathode (S-CNT). Thus, we believe that our new cathode design will be useful in developing stable, high-energy Li-S batteries.

Electrochemical Study of Bimetal Organic Frameworks with Graphene Oxide for Lithium-Sulfur Cells as Nanoarchitectonics.

We studied that hybrid material of metal organic framework, using two different metals (bimetal organic frameworks), containing graphene oxide (GO) as a sulfur immobilizing host was successfully synthesized by hydrothermal reaction. Composites were prepared using ligands of varying ratios to observe the structure properties depending on the amount of ligand used. Field emission scanning electron microscopy (FE-SEM), Fourier Transform Infra-Red Spectroscopy (FT-IR), and X-ray diffraction (XRD) were conducted to determine the morphology and micro-structure of the composite. Electrochemical properties were characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge tests. Based on these study, bimetal organic frameworks showed different morphology by ligand amounts and the enhanced performance for Li-S battery cathode.

Synthesis of Bi-Metallic Organic Frameworks and Their Capacitive Behaviors According to Metal Mixing Ratio.

Metallic organic frameworks (MOFs) with mixed metals has attracted attention as electrochemical energy storage material because it has high specific surface area, synergy of two metals, and a new crystal structure different from that of conventional MOF. In this study, we synthesized MOFs, including nickel and zinc, by hydrothermal method at a time. We investigated the effect of two metal ratios on the capacitive behavior. Through the structure and morphology analysis, it was found that Ni-Zn-MOF forms a completely different crystal structure from MOF using one metal, and found that it is a porous material. As a result of electrochemical measurements with cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD), the specific capacitance of Ni-Zn-MOF 2:1 with a nickel to zinc ratio of 2:1 was 616 F g-1 at a current density was 1 A g-1.

A Mesoporous Chelating Polymer-Carbon Composite for the Hyper-Efficient Separation of Heavy Metal Ions.

The removal of heavy-metal ions from wastewater is an important objective from a public-health perspective, and chelating agents can be used to achieve this aim. Herein, we report the synthesis of mesoporous carbon as a chelating polymer host using nanoarchitectonics approach. Carboxymethylated polyethyleneimine, a chelating polymer, was incorporated into the mesopore walls of mesoporous carbon to create a polymer-mesoporous-carbon composite. Nitrogen adsorption- desorption experiments and scanning electron microscopy (SEM) were used to illustrate the structural advantages of the composite. Co2+ adsorption by the composite material was examined using cobalt nitrate solutions at pH 3. The study revealed that the Co2+-absorption data are most closely modeled by the Langmuir isotherm. The maximum adsorption capacity, calculated by linear regression, was determined to be about 40 mg-Co/g-composite at pH 3. The composite exhibited about a six-times higher adsorption capacity toward a dilute Co solution (12.5 ppm) than that of the pristine mesoporous carbon. In addition, the composite showed a substantially higher distribution coefficient (Kd = 1.54×105) compared to that (Kd = 2.05×10²) of the mesoporous carbon. Overall, we expect that the mesoporous composite, with its large mesopores (~20 nm), will be in high demand for adsorption applications.

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.

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.

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.

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).

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.

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.