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 (K_d = 1.54×10⁵) compared to that (K_d = 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.

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.

Cerebral Ketones Detected by 3T MR Spectroscopy in Patients with High-Grade Glioma on an Atkins-Based Diet

BACKGROUND AND PURPOSE

Ketogenic diets are being explored as a possible treatment for several neurological diseases, but the physiologic impact on the brain is unknown. The objective of this study was to evaluate the feasibility of 3T MR spectroscopy to monitor brain ketone levels in patients with high-grade gliomas who were on a ketogenic diet (a modified Atkins diet) for 8 weeks.

MATERIALS AND METHODS

Paired pre- and post-ketogenic diet MR spectroscopy data from both the lesion and contralateral hemisphere were analyzed using LCModel software in 10 patients.

RESULTS

At baseline, the ketone bodies acetone and β-hydroxybutyrate were nearly undetectable, but by week 8, they increased in the lesion for both acetone (0.06 ± 0.03 ≥ 0.27 ± 0.06 IU, P = .005) and β-hydroxybutyrate (0.07 ± 0.07 ≥ 0.79 ± 0.32 IU, P = .046). In the contralateral brain, acetone was also significantly increased (0.041 ± 0.01 ≥ 0.16 ± 0.04 IU, P = .004), but not β-hydroxybutyrate. Acetone was detected in 9/10 patients at week 8, and β-hydroxybutyrate, in 5/10. Acetone concentrations in the contralateral brain correlated strongly with higher urine ketones (r = 0.87, P = .001) and lower fasting glucose (r = -0.67, P = .03). Acetoacetate was largely undetectable. Small-but-statistically significant decreases in NAA were also observed in the contralateral hemisphere at 8 weeks.

CONCLUSIONS

This study suggests that 3T MR spectroscopy is feasible for detecting small cerebral metabolic changes associated with a ketogenic diet, provided that appropriate methodology is used.

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 (S_sep) to sulfur in cathode (S₊). At the high S_sep/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.

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.

CXCR3 ligands in pleural fluid as markers for the diagnosis of tuberculous pleural effusion

SETTING

A tertiary care academic medical centre.

OBJECTIVE

To evaluate the clinical usefulness of C-X-C motif chemokine receptor 3 (CXCR3) ligands in tuberculous pleural effusion (TPE).

DESIGN

We recruited 336 patients with pleural effusion due to various causes. Concentrations of interferon-gamma (IFN-γ) and the CXCR3 ligands CXCL9 and CXCL11 were determined using enzyme immunoassays; adenosine deaminase (ADA) activity was measured in pleural fluid and serum.

RESULTS

TPE was diagnosed in 106 patients. Non-TB conditions included lung cancer (n = 95), para-pneumonic effusion (n = 52), non-lung malignancy (n = 30), other exudate (n = 24) and transudate (n = 29) disorders. All marker levels in serum samples and pleural fluid were significantly higher in the TPE group. Analyses of receiver operating characteristic curves for differentiating TPE from non-TB effusions produced the following results for the area under the curve (AUC) for CXCL9, CXCL11, IFN-γ and ADA, respectively: 0.982, 0.952, 0.982, and 0.952. Marker AUCs in lymphocytic exudates were also high. Combining the levels of CXCL9, IFN-γ and ADA in pleural fluid improved the diagnostic performance. Serum levels of CXCL9 had the highest AUC (0.848) for diagnosing TPE.

CONCLUSION

Levels of CXR3 ligands in pleural effusion are useful for diagnosing TPE.

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).

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.