Synthesis of Iron Sulfide Nanocrystals Encapsulated in Highly Porous Carbon-Coated CNT Microsphere as Anode Materials for Sodium-Ion Batteries.

Highly porous carbon materials with a rationally designed pore structure can be utilized as reservoirs for metal or nonmetal components. The use of small-sized metal or metal compound nanoparticles, completely encapsulated by carbon materials, has attracted significant attention as an effective approach to enhancing sodium ion storage properties. These materials have the ability to mitigate structural collapse caused by volume expansion during the charging process, enable short ion transport length, and prevent polysulfide elution. In this study, a concept of highly porous carbon-coated carbon nanotube (CNT) porous microspheres, which serve as excellent reservoir materials is suggested and a porous microsphere is developed by encapsulating iron sulfide nanocrystals within the highly porous carbon-coated CNTs using a sulfidation process. Furthermore, various sulfidation processes to determine the optimal method for achieving complete encapsulation are investigated by comparing the morphologies of diverse iron sulfide-carbon composites. The fully encapsulated structure, combined with the porous carbon, provides ample space to accommodate the significant volume changes during cycling. As a result, the porous iron sulfide-carbon-CNT composite microspheres exhibited outstanding cycling stability (293 mA h g-1 over 600 cycles at 1 A g-1 ) and remarkable rate capability (100 mA h g-1 at 5 A g-1 ).

Synthesis of Graphitic Carbon Coated ZnPS3 and its Superior Electrochemical Properties for Lithium and Sodium Ion Storage.

Graphitic carbon-coated ZnPS3 is prepared via direct phosphosulfurization and high energy mechanical milling (HEMM) with multiwall carbon nanotubes (MWCNTs) and first introduced as an anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The HEMM process with MWCNTs reduces the particle size of as-synthesized ZnPS3 bulk to 100-500 nm and yields the ≈5 nm thick graphitic carbon coated ZnPS3 nanoparticles, which are the nanocomposites of 5 nm sized nanocrystallites embedded in the amorphous matrix. The ZnPS3 electrode undergoes the combined conversion and alloying reactions with Li and Na ions and exhibits high initial discharge and charge capacities in both LIBs and SIBs. The graphitic carbon-coated ZnPS3 electrode exhibits excellent high-rate capability and long-term cyclability. The superior electrochemical properties can be attributed to high electrical conductivity, high Li ion mobility, and high reversibility and structural stability derived from the graphitic carbon-coated nanoparticles. This study demonstrates that the novel graphitic carbon-coated ZnPS3 is a promising anode material for both LIBs and SIBs and the graphitic carbon coating methodology by HEMM is expected to apply to the various metal oxides, sulfides, and phosphides.

Energy-Efficient Ingestible Drug Delivery System in the Dynamic Gastrointestinal Environment.

Ingestible electronics are promising platforms for on-demand health monitoring and drug delivery. However, these devices and their actuators must operate in the gastrointestinal (GI) environment, which has a pH range of 1 to 8. Drug delivery systems using electrochemical dissolution of metal films are particularly susceptible to pH changes. Optimal operation in this dynamic environment stands to transform our capacity to help patients across a range of conditions. Here we present an energy-efficient ingestible electronic electrochemical drug delivery system to support subjects through operation in this dynamic environment. The proposed system consists of a drug reservoir sealed with an electrochemically dissolvable gold membrane and an electronic subsystem. An electronic subsystem controls the rate of gold dissolution by sensing and adapting to the pH of the GI environment and provides an option for energy-efficient drug delivery, reducing energy consumption by up to 42.8 %. Integrating the electronics with electrochemical drug delivery enables the proposed system to adapt to the dynamic physiological environments which makes it suitable for drug and/or therapeutic delivery at different locations in the GI tract.

Fully Automated Segmentation of Human Eyeball Using Three-Dimensional U-Net in T2 Magnetic Resonance Imaging.

Purpose: To develop and validate a fully automated deep-learning-based tool for segmentation of the human eyeball using a three-dimensional (3D) U-Net, compare its performance to semiautomatic segmentation ground truth and a two-dimensional (2D) U-Net, and analyze age and sex differences in eyeball volume, as well as gaze-dependent volume consistency in normal subjects. Methods: We retrospectively collected 474 magnetic resonance imaging (MRI) scans, including different gazing scans, from 119 patients. A 10-fold cross-validation was applied to separate the dataset into training, test, and validation sets for both the 3D U-Net and 2D U-Net. Performance accuracy was measured using four quantitative metrics compared to the ground truth, and Bland-Altman plot analysis was conducted. Age and sex differences in eyeball volume and variability in eyeball volume differences across gazing directions were analyzed. Results: The 3D U-Net outperformed the 2D U-Net with mean accuracy scores >0.95, showing acceptable agreement in the Bland-Altman plot analysis despite a tendency for slight overestimation (mean difference = -0.172 cm³). Significant sex differences and age effects on eyeball volume were observed for both methods (P < 0.05). No significant volume differences were found between the segmentation methods or within each method for the different gazing directions. Significant differences in performance accuracy were identified among the five gazing directions, with the upward direction showing a notably lower performance. Conclusions: Our study demonstrated the effectiveness of 3D U-Net human eyeball volume segmentation using T2-weighted MRI. The robustness and reliability of 3D U-Net across diverse populations and gaze directions support enhanced ophthalmic diagnosis and treatment strategies. Translational Relevance: Our findings demonstrate the feasibility of using the proposed 3D U-Net model for the automatic segmentation of the human eyeball, with potential applications in various ophthalmic research fields that require the analysis of 3D geometric eye globe shapes or eye movement detection.

Confinement Effects of Hollow Structured Pt-Rh Electrocatalysts toward Complete Ethanol Electrooxidation.

In the anodic ethanol oxidation reaction (EOR) for direct ethanol fuel cells, the coverage of hydroxide (OHads) is a major adsorbent competing with C-C bond cleavage, which is necessary for complete ethanol oxidation (C1-pathway) and durability. Beyond utilizing a less-alkaline electrolyte that causes ohmic losses, an alternative strategy to optimize OHads coverage is to intentionally exploit local pH changes near the electrocatalyst surface that are governed by a combination of released H+ during EOR and OH- mass transport from the bulk solution. Here, we manipulate the local pH swing by fine-tuning the electrode porosity with Pt1-xRhx hollow sphere electrocatalysts based on particle size (250 and 350 nm) and mass loading. With the smaller size of 250 nm, Pt0.5Rh0.5 (∼50 µg cm-2) shows a high activity of 1629 A gPtRh-1 (2488 A gPt-1) in a 0.5 M KOH-containing electrolyte, which is ∼50% higher than the most active binary catalysts to date. Moreover, a higher C1-pathway Faradaic efficiency (FE) of 38.3% and 80% longer durability are achieved with a 2-fold increase in mass loading. In the more porous electrodes, a local acidic environment created by hindered OH- mass transport better optimizes OHads coverage, providing more active sites for the desired C1-pathway and a continuous EOR.

Chiral separation and molecular modeling study of decursinol and its derivatives using polysaccharide-based chiral stationary phases.

Plant-based bioactive substances have long been used to treat inflammatory ailments, owing to their low toxicity and cost-effectiveness. To enhance plant treatment by eliminating undesirable isomers, optimizing the chiral separation techniques in pharmaceutical and clinical studies is important. This study reported a simple and effective method for chiral separation of decursinol and its derivatives, which are pyranocoumarin compounds with anti-cancer and anti-inflammatory properties. Baseline separation (Rs >1.5) was achieved using five different polysaccharide-based chiral stationary phases (CSPs) that differed in chiral origin, chiral selector chemistry, and preparation technique. To separate all six enantiomers simultaneously, n-hexane and three alcohol modifiers (ethanol, isopropanol, and n-butanol) were used as mobile phases in the normal-phase mode. The chiral separation ability of each column with various mobile phase compositions was compared and discussed. As a result, amylose-based CSPs with linear alcohol modifiers demonstrated superior resolution. Three cases of elution order reversal caused by modifications of CSPs and alcohol modifiers were observed and thoroughly analyzed. To elucidate the chiral recognition mechanism and enantiomeric elution order (EEO) reversal phenomenon, detailed molecular docking simulations were conducted. The R- and S-enantiomers of decursinol, epoxide, and CGK012 exhibited binding energies of -6.6, -6.3, -6.2, -6.3, -7.3, and -7.5 kcal/mol, respectively. The magnitude of the difference in binding energies was consistent with the elution order and enantioselectivity (α) of the analytes. The molecular simulation results demonstrated that hydrogen bonds, π-π interactions, and hydrophobic interactions have a significant impact on chiral recognition mechanisms. Overall, this study presented a novel and logical approach of optimizing chiral separation techniques in the pharmaceutical and clinical industries. Our findings could be further applied for screening and optimizing enantiomeric separation.

Mapping the electrocatalytic water splitting activity of VO2 across its insulator-to-metal phase transition.

The electrocatalytic water splitting activity of V-based oxides has been rarely investigated, even though several polymorphs in VO2 are expected to exhibit different electrocatalytic activities depending on their crystal and electronic structures. The rutile structure of VO2(R), showing metallic character, is a good candidate for a new electrocatalyst since it undergoes insulator-to-metal transition (IMT) from the insulating VO2(M1) at a low temperature of 68 °C, and involves a substantially increased electrical conductivity by three orders of magnitude. The extensive improvements in the electrocatalytic activity for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) are confirmed when the IMT is induced where the overpotential (η10) is reduced from 1056 mV to 598 mV in the OER and 411 mV to 136 mV in the HER, respectively. This improvement is attributed to the increased electrochemically active surface area (ECSA), reduced charge transfer resistance, and increased electron density, driven by the IMT to the metallic VO2(R) phase.

Determination of enantiomeric impurity of tenofovir disoproxil fumarate on a cellulose tris(3,5-dichlorophenyl-carbamate) chiral stationary phase and the characterization of its related substances.

A simple and reliable high-performance liquid chromatography method was developed to determine the enantiomeric impurity of tenofovir disoproxil fumarate, an orally bioavailable prodrug of tenofovir, commonly used for the treatment of human immunodeficiency virus and hepatitis B. Tenofovir disoproxil and its enantiomer, were completely separated on a Chiralpak IC column (3 µm, 100 × 4.6 mm, i.d.). The chiral separation was achieved using a mobile phase containing n-hexane, ethanol, methanol, and triethylamine 65/25/10/0.1 (v/v/v/v) at a flow rate of 0.6 mL/min. Ideally, the reversal of enantiomer elution order was achieved on the Chiralpak IC column, to allow the elution of the minor enantiomeric impurity before the major component. Moreover, the proposed method was able to discriminate the active ingredient from the related substances available in the tenofovir disoproxil fumarate raw materials. These compounds were isolated and structurally elucidated by MS and nuclear magnetic resonance. Based on the spectral data, the structures of related substances were confirmed as tenofovir isoproxil monoester and fumaric acid. The high-performance liquid chromatography method was optimized by the design of experiment approach and successfully validated following the International Conference on Harmonization guideline. Proposed method was effectively applied for the quantification of enantiomeric impurity in tenofovir disoproxil fumarate raw materials.

A capillary electrophoresis method for the determination of the linagliptin enantiomeric impurity.

Linagliptin is a highly specific, long-acting inhibitor that is used as an orally administrable agent for type-2 diabetes treatment. Because only the R-enantiomer is of clinical use, we developed a capillary electrophoresis method for the determination of the enantiomeric impurity of this compound. Carboxymethyl-ß-cyclodextrin was selected as the chiral selector for the separation of linagliptin enantiomers. Design of experiments and desirability functions were used for the analytical optimization, which was focused on understanding and improving the electrophoretic process. The effects of significant parameters (background electrolyte concentration and pH, cyclodextrin concentration, temperature, and voltage) were thoroughly investigated. The complete separation of linagliptin and its enantiomeric impurity with baseline resolution was achieved within 10 min on an uncoated fused-silica capillary (50 µm inner diameter, 365 µm outer diameter, 64.5/56 cm in total/ effective length) maintained at 25°C, under an applied voltage of 28.0 kV. The background electrolyte contained 70 mM sodium acetate and 4.7 mM carboxymethyl-ß-cyclodextrin, and the pH was adjusted to 6.10. The method was validated, and a limit of quantitation of 0.05% for the impurity was estimated.

A MnV2O6/graphene nanocomposite as an efficient electrocatalyst for the oxygen evolution reaction.

A MnV2O6/graphene nanocomposite was fabricated through hydrothermal synthesis and high energy milling to introduce it as an efficient OER electrocatalyst. The MnV2O6/graphene nanocomposite with 20 wt% graphene exhibited superior electrocatalytic OER performance with a low overpotential and high stability and durability in 1 M KOH aqueous solution, exhibiting even after 1000 CV cycles.

A P2-type Na0.7(Ni0.6Co0.2Mn0.2)O2 cathode with excellent cyclability and rate capability for sodium ion batteries.

A new P2-type Na0.7(Ni0.6Co0.2Mn0.2)O2 was prepared via co-precipitation and its electrochemical properties as a cathode for sodium ion batteries were compared with those of O3-type Na(Ni0.6Co0.2Mn0.2)O2, focusing on phase stability and cycling performance. The P2-type delivered a high capacity of 108 mA h g-1 after 300 cycles at 2C.

Stable Silicon Anode for Lithium-Ion Batteries through Covalent Bond Formation with a Binder via Esterification.

Silicon (Si) is considered to be one of the most promising anode candidates for next-generation lithium-ion batteries because of its high theoretical specific capacity and low discharge potential. However, its poor cyclability, caused by tremendous volume change during cycling, prevents commercial use of the Si anode. Herein, we demonstrate a high-performance Si anode produced via covalent bond formation between a commercially available Si nanopowder and a linear polymeric binder through an esterification reaction. For efficient ester bonding, polyacrylic acid, composed of -COOH groups, is selected as the binder, Si is treated with piranha solution to produce abundant -OH groups on its surface, and sodium hypophosphite is employed as a catalyst. The as-fabricated electrode exhibits excellent high rate capability and long cycle stability, delivering a high capacity of 1500 mA h g-1 after 500 cycles at a high current density of 1000 mA g-1 by effectively restraining the susceptible sliding of the binder, stabilizing the solid electrolyte interface layer, preventing the electrode delamination, and suppressing the Si aggregation. Furthermore, a full cell is fabricated with as-fabricated Si as an anode and commercially available LiNi0.6Mn0.2Co0.2O2 as a cathode, and its electrochemical properties are investigated for the possibility of practical use.

Solid solution phosphide (Mn1-xFexP) as a tunable conversion/alloying hybrid anode for lithium-ion batteries.

The substitutional solid solution Mn1-xFexP compounds between alloying reaction-type MnP and conversion reaction-type FeP are successfully synthesized via facile high energy mechanical milling and their electrochemical properties as an anode for lithium ion batteries (LIBs) are investigated. A complete solid solution is formed between two end members and the Mn1-xFexP solid solution phosphide electrodes show an enhanced electrochemical performance, delivering a capacity of 360 mA h g-1 after 100 cycles at a high current density of 2 A g-1 when the advantages of the two reaction mechanisms are beneficially combined. These synergistic effects resulted from the in situ generated nanocomposite of the Li-Mn-P alloying element and the Fe nano-network in combination with the surrounding amorphous lithium phosphide, which effectively buffers the accompanying volume variation, hinders the aggregation of the alloying element, and ensures the electron and ion transport.

Mesoporous Si-Cu nanocomposite anode for a lithium ion battery produced by magnesiothermic reduction and electroless deposition.

Copper deposited mesoporous silicon was fabricated by magnesiothermic reduction and electroless deposition and its electrochemical properties as an anode for lithium ion batteries were investigated. The 300-400 nm sized mesoporous Si particles were synthesized by magnesiothermic reduction of SiO2 nanospheres prepared by the Stöber method. The mesopores of Si particles were effectively decorated with Cu using Sn sensitization/Pd activation and subsequent Cu electroless deposition. The homogeneous distribution of Cu inside the mesoporous Si particles was confirmed by high resolution transmission electron microscopy images and energy dispersive spectroscopy mapping on the cross-sectional specimen prepared by a focused ion beam. The mesoporous Si-Cu nanocomposite exhibited high initial Coulombic efficiency, long cycle stability, and high rate capability, delivering a high capacity of 1569 mAh g-1 after 200 cycles at the current density of 1000 mA g-1. The improved electrochemical performance in a mesoporous Si-Cu nanocomposite was attributed to the high electrical conductivity, high Li+ ion mobility, and structural stability to restrict the aggregation and pulverization of active materials.

The Role of Zr Doping in Stabilizing Li[Ni0.6 Co0.2 Mn0.2 ]O2 as a Cathode Material for Lithium-Ion Batteries.

Ni-rich layered LiNi1-x-y Cox Mny O2 systems are the most promising cathode materials for high energy density Li-ion batteries (LIBs). However, Ni-rich cathode materials inevitably suffer from rapid capacity fading and poor rate capability owing to structural instability and unstable surface side reactions. Zr doping has proven to be an effective method to enhance the cycle and rate performances by stabilizing the structure and increasing the Li+ diffusion rate. Herein, effects of Zr-doping on the structural stability and Li+ diffusion kinetics are thoroughly investigated in LiNi0.6 Co0.2 Mn0.2 O2 (LNCM) cathode material using atomic-resolution scanning transmission electron microscopy imaging, XRD Rietveld refinement, and density functional theory calculations. Zr doping mitigates the degree of cation mixing, decreases the structural transformation, and facilitates Li+ diffusion resulting in improved cyclic performance and rate capability. Based on the obtained results, an atomistic model is proposed to explain the effects of Zr doping on the structural stability and Li+ diffusion kinetics in LNCM cathode materials.

Superior electrochemical sodium storage of V4P7 nanoparticles as an anode for rechargeable sodium-ion batteries.

V4P7 nanoparticles were synthesized via high-energy mechanical milling and their electrochemical properties as an anode for sodium-ion batteries were studied and compared with those of VO2(B)/Na and V4P7/Li cells, focusing on the electrochemical reaction mechanism and cycle performance. The V4P7 showed excellent cycling behavior even without any conductive material.

Simultaneous determination of 14 oral antihyperglycaemic drugs in human urine by liquid chromatography-tandem mass spectrometry.

A simple, sensitive, and rapid assay based on hydrophilic interaction liquid chromatography (HILIC) with tandem mass spectrometry was developed and validated for the simultaneous determination of metformin and 13 other oral antihyperglycaemic drugs in human urine using metoprolol as an internal standard. A simple sample clean-up procedure using the "dilute and shoot" approach enabled fast and reliable analysis. Chromatographic separation was performed on a HILIC column using an elution gradient of mobile phase A, composed of 1 mM ammonium formate (pH 5), and mobile phase B, composed of acetonitrile, at a flow rate of 0.35 mL/min. Quantitation was performed on a triple quadrupole mass spectrometer operated in multiple reaction monitoring mode by using electrospray ionization in positive ion mode. The total chromatographic run time was 20 min. Calibration curves for each analyte were linear over concentration ranges of 2-300, 5-400, or 20-500 ng/mL, with a coefficient of determination above 0.99. The method was validated for selectivity, sensitivity, recovery, linearity, accuracy and precision, system suitability, robustness, and stability. Inter-batch and intra-batch coefficients of variation across four validation runs were ≤ 13.62%. The present method was successfully applied for the analysis of metformin and nateglinide in urine samples after their oral administration to healthy human subjects under fasted conditions.

Superior sodium storage performance of reduced graphene oxide-supported Na3.12Fe2.44(P2O7)2/C nanocomposites.

In this study, a reduced graphene oxide-supported Na3.12Fe2.44(P2O7)2/C nanocomposite was successfully synthesized by a sol-gel method and a subsequent heat-treatment process. Not only did the composite undergo a highly reversible electrochemical reaction, but it also exhibits superior rate capability and long-term cyclic stability as a Na-ion battery cathode.

Determination of S-(-)-lansoprazole in dexlansoprazole preparation by capillary zone electrophoresis.

Capillary zone electrophoresis was successfully applied to the enantiomeric purity determination of dexlansoprazole using sulfobutyl ether-ß-cyclodextrin and methyl-ß-cyclodextrin as chiral selectors. Separations were carried out in a 50 µm, 64/56 cm fused-silica capillary. The optimized conditions included 90 mM phosphate buffer, pH 6.0, containing 30 mM sulfobutyl ether-ß-cyclodextrin, 20 mM methyl-ß-cyclodextrin as background electrolyte, an applied voltage of 25 kV and a temperature of 16 °C, detection was at 280 nm. The assay was validated for the S-(-)-lansoprazole in the range of 0.2-1.0%. The limit of detection was 0.07%, the limit of quantitation was 0.20%, relative to a total concentration of 4.0 mg mL-1. Intra-day precision varied between 1.72 and 2.07%. Relative standard deviations of inter-day precision ranged between 1.62 and 1.96% for peak area ratio. The assay was applied for the determination of the chiral purity of dexlansoprazole capsules. Recovery in capsules was ranged between 101.7 and 103.1%.

Determination of rabeprazole enantiomers in commercial tablets using immobilized cellulose-based stationary phase.

Rabeprazole is one of the latest proton-pump inhibitors used for treatment of several gastrointestinal disorders. For therapeutic applications, rabeprazole has been administered as a mixture of R-(+) and S-(-) enantiomers. Owing to pharmacological and toxicological differences between stereoisomers, chiral recognition has now become an integral part of drug research and development. A simple and rapid liquid chromatographic method for enantioselective separation and determination of R-(+) and S-(-) enantiomers of rabeprazole in bulk drug and pharmaceutical formulations was developed. Chiralpak IC (150 × 4.6 mm, 5 µm) column and µmobile phase containing hexane:ethanol:ethylenediamine (30:70:0.05 v/v) in an isocratic mode yielded baseline separation with resolution greater than 6.0 at 35 °C. Effects of additives and n-hexane were evaluated. Optimized condition was validated as per ICH guidelines. The method has good linearity, high sensitivity with LOD was 0.01 µg/mL and LOQ was 0.03 µg/mL for both enantiomers. Intra-day precision varied between 0.44 and 1.79% for S-(-) enantiomer, 0.65 and 1.97% for R-(+) enantiomer. Relative standard deviations of inter-day precision were less than 1.81% for both enantiomers. The percentage recovery for both enantiomers of rabeprazole ranged between 99.81 and 101.95%, 98.82 and 101.36% in material and tablets, respectively. The method was successfully applied to determine content of each enantiomer in commercial tablets.