Acetonitrile Research Articles

Solvent Engineering in Ligand Exchange of the Hole Transport Layer Enables High-Performance PbS Quantum Dot Solar Cells.

The performance of lead sulfide colloidal quantum dot (PbS-CQD) solar cells has long been hindered by interface defects in the transport layer. Traditionally, 1,2-ethanedithiol (EDT), used in solid-state ligand exchange, has been a common choice as the hole transport layer (HTL) in many PbS-CQD solar cells. However, the rapid reaction rate and chain length mismatch (shorter-chain EDT versus longer-chain oleic acid) during the ligand exchange process often introduce crack defects in the HTL film, resulting in an unexpected low performance. In this work, ethyl acetate (EA) was introduced into acetonitrile (ACN) solution to slow down the ligand exchange rate. With EA's assistance, a high-quality HTL film with fewer cracks was achieved, leading to a reduced trap density from 2.26 × 1016 cm-3 to 1.85 × 1016 cm-3. Consequently, this led to an improved VOC by 27.5 mV and an increased power conversion efficiency (PCE) from 11.01% to 12.16%.

Acetonitrile-Based Highly Concentrated Electrolytes for High-Power Organic Sodium-Ion Batteries.

Sodium croconate, a high-voltage organic cathode material, can be applied to high-energy-density and cost-effective organic sodium-ion batteries (OSIBs) as an alternative to traditional lithium-ion batteries. However, organic molecular cathodes generally dissolve into the electrolyte, leading to poor cyclability. Thus, an electrolyte that can address the present limitations and further facilitate the fabrication of highly reversible OSIBs must be developed. To address this gap in the literature, in this study, we demonstrate an acetonitrile (AN)-based highly concentrated electrolyte (HCE) with sodium bis(fluorosulfonyl)imide (NaFSI). This electrolyte has an ionic conductivity of 12.1 mS cm-1, which is higher than those of previously reported HCEs. Moreover, the developed HCE (NaFSI:AN molar ratio of 1:2.7) exhibits a high Na+ transference number of 0.49. A full-cell OSIB bearing this electrolyte demonstrates high-power operation with improved capacity retention. The solvent-free electrolyte with the solvation structure of the [2Na+-FSI-] aggregate suppresses the dissolution of organic molecules, leading to their high performance.

Solubility and solution thermodynamics of nortriptyline hydrochloride in organic solvents: Experiment and correlation

The present study is focused on the determination of the equilibrium solubility of nortriptyline hydrochloride (NTT) (Form II) in 10 pure solvents essential for chemical and pharmaceutical industry: ethanol (EtOH), n-propanol (n-PrOH), n-butanol (n-BuOH), isopropanol (i-PrOH), acetonitrile (ACN), dimethyl formamide (DMF), acetone (Ace), methyl ethyl ketone (MEK), tetrahydrofuran (THF), n-octanol (n-OctOH). The solvents were selected on the principles of their different molecular structures, polarities and properties in order to provide the information useful for drug crystallization and purification. The experiments were carried from 288.15K to 318.15(±0.1) K at 5K intervals by the gravimetric and spectrophotometric methods. The following sequence of the solvents according to the values of NTT solubility at a standard temperature of 298.15K was revealed: EtOH>n-PrOH≥n-BuOH>DMF>n-OctOH≥i-PrOH>THF>Ace>MEK>ACN. The influence of the solvent polarity on the solubility of NTT in comparison with the structurally similar drug amitryptiline hydrochloride from the literature sources was revealed. The results on the NTT experimental solubility were correlated by the thermodynamic models: van't Hoff equation, modified Apelblat equation, λh equation, two-suffix Margules model, Wilson model, and NRTL model. The apparent dissolution thermodynamic functions were calculated using the van’t Hoff equation. The mixing thermodynamic parameters were disclosed and discussed in relation to the driving forces of the processes.

A chemodosimetric chemosensor for the ratiometric detection of nerve agent-mimic DCP in solution and vapor phases.

Nerve agents are among the most deadly and lethal chemical warfare agents (CWAs). Rapid identification is crucial for specialized individuals to take action against dangerous drugs. This paper describes the synthesis and characterisation of a probe (MNFZ) based on the methoxy naphthalene-furoic hydrazide group. The probe rapidly (100 s) detects and quantifies the nerve-agent simulant diethyl chlorophosphate (DCP) in both solution and vapor phases. This sensor uses a new recognition center, furoic hydrazide, where the nitrogen atom of the imine group (CN) attacks the electrophilic core phosphorus atom of DCP, followed by the hydrolysis of the imine group in the acetonitrile (ACN) solution to produce the corresponding aldehyde MNPA. The development of ICT character resulted in a distinct red-shifted ratiometric fluorescence response to DCP, with a very low limit of detection (12.2 nM). The probe is an efficient chemosensor due to its high selectivity over other organophosphorus compounds as well as its chemical stability across a wide pH range. DFT calculations, 1H NMR and HRMS were performed to finalize the sensing mechanism. Lastly, the as-designed sensor was successfully used to build a highly sensitive portable kit in test strips and a cotton biopolymer for simple and safe real-time monitoring of DCP.

Rapid and Environment-Friendly LC-MS/MS for Simultaneous Analysis of Amino Acids in Veterinary Medicine.

Amino acid supplements are crucial for animal health and productivity. Traditional analysis methods face limitations like complexity, long testing times and toxic reagents. Therefore, a more efficient and reliable method is needed. This study aimed to develop and validate an efficient method for the simultaneous analysis of eight amino acids commonly used in veterinary medicine: alanine, arginine, glutathione, lysine, ornithine, methionine, threonine and tryptophan. We analysed eight veterinary amino acid preparations. From 100 registered products, we selected 35. After confirming ingredients, we diluted them to 1mg/L with 50% acetonitrile (ACN) and filtered them using a 0.2µm RC filter for liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis. All analytes showed excellent linearity (r2>0.99) within 0-10mg/L. The limits of detection (LOD) ranged from 0.04 to 0.83mg/L, and the limits of quantification (LOQ) ranged from 0.12 to 2.52mg/L. Average recovery ranged from 92.96% to 105.61%, with relative standard deviations (RSD) from 0.27% to 3.50%, meeting CD 2002/657/EC standards. Six out of the 35 products (17.14%) did not meet regulations. The method developed in this study offers an efficient and reliable approach for the simultaneous analysis of essential amino acids in veterinary medicine. Implementing this method can improve the quality control of amino acid products, enhancing animal health and productivity. This study also highlights the need for stringent domestic management and continuous monitoring. By overcoming traditional technique limitations, this validated method ensures the quality and efficacy of amino acid supplements in the veterinary industry.

Low-frequency (0-450 cm-1) dynamics of n-alkyl cyanide liquids studied by optical Kerr effect spectroscopy and density functional theory.

This article presents a study of the dynamics of n-alkyl cyanides (CnH2n+1CN with n = 1-5) in the 0-450 cm-1 spectral region as a function of alkyl chain length. The spectra were measured using femtosecond optical Kerr effect (OKE) spectroscopy. The OKE spectra are characterized by a broad band in the 0-150 cm-1 region arising mainly from intermolecular modes and by narrow bands in the 150-450 cm-1 region arising from intramolecular modes. The intramolecular bands in the OKE spectra are in good agreement with the bands in simulated spectra obtained from density functional theory calculations. For cyanide molecules with long alkyl chains (n = 3-5), a low frequency intramolecular band associated with a torsional vibrational mode overlaps with the intermolecular band. Applying multicomponent line-shape analysis to the broad low-frequency band allowed us to obtain the intermolecular component of the band. We find the frequency and amplitude of the intermolecular band decrease with increasing chain length. Based on previous theoretical studies of the OKE spectrum of methyl cyanide and OKE reorientational studies of n-alkyl cyanides, we show that the dependence of the frequency of the intermolecular band on alkyl chain length is consistent with the band being primarily due to the hindered rotational motion of the molecules in the extended configuration about an axis perpendicular to the long axis of the molecule. The dependence of the amplitude of the intermolecular band on alkyl chain length is a mass effect associated with suppression of the collision-induced contribution to the intermolecular band.

Stiff-Stilbene-Linked Bis-Cholesterol: Synthesis and Investigation of Its Supramolecular Gelation and Photophysical Behaviors.

Here, we report the design, synthesis, and comprehensive characterization of the bis-cholesterol supramolecular gelator, which contains photochromic stiff-stilbene as a bridging unit. The cis-isomer of stiff-stilbene bridged bis-cholesterol (Z-D) was first synthesized with a systematic design, which can be further converted into its trans-isomer (E-D) with a high degree of efficiency (ca. 100%) upon exposure to 385 nm UV light. Unusual gelation behavior was observed for Z-D, which exhibited supergelator properties in mixed solvents of acetonitrile (ACN)/dichloromethane (DCM) (v/v = 1:1), DCM/MeOH (v/v = 1:2), ACN/CHCl3 (v/v = 2:1), and CHCl3/MeOH (v/v = 1:2), with minimum gelation concentrations (MGCs) as low as 0.2 w/v%. These gels formed rapidly at room temperature without the aid of any mechanical forces upon the addition of an antisolvent into the vial containing the gelator and its dissolving solvent. The formation of the self-assembled gel was primarily driven by hydrogen bonding, van der Waals forces, and dipole-dipole interactions, as confirmed by 1H NMR, Fourier transform infrared spectroscopy (FT-IR), and UV-vis spectroscopies. The gelator molecule Z-D entraps organic solvents and organizes itself into three-dimensional (3D) fibrillar networks in various single and mixed solvents, as confirmed by scanning electron microscopy (SEM) analysis. Upon irradiation with 385 nm light, the gel networks disintegrated into a precipitate suspension, resulting in the transformation of the fibrous structures into irregular spherical-like aggregates. This proves that the structural conformation changes in the gelator significantly influence the resulting self-assembled structures. Overall, the findings present in this study pave the way for the future development of novel light-responsive bis-cholesterol-based gelators, especially in their Z-isomeric form.

Stabilizing SPAN in Non-Flammable Acetonitrile Electrolytes for Long-Life Graphite||SPAN Batteries.

Sulfurized polyacrylonitrile (SPAN) presents an opportunity to replace elemental sulfur as a "shuttle-free" cathode for secondary Li-S batteries, which can be an ideal choice for stationary energy storage due to its abundance, low cost, and sustainability. The electrolyte options for the state-of-the-art SPAN batteries have been limited to the flammable carbonate and ether ones, which raises safety concerns. Here, we explored the use of a non-flammable acetonitrile (AN) electrolyte for SPAN battery for the first time and identified the irreversible cleavage of C-S bonds of SPAN as the main reason for the failure of SPAN in AN electrolyte. Fortunately, by introducing 10 wt % fluoroethylene carbonate into the AN electrolyte, the bond cleavage in SPAN is suppressed and a stable cathode electrolyte interface is formed, both contributing to stabilizing the structure of SPAN during electrochemical process. Consequently, we achieved a stable cycling for 900 cycles in Li||SPAN cells. Moreover, by pairing with a pre-lithiated graphite (pGr) anode, the newly formulated electrolyte enables extended cycle life for 1500 cycles with a capacity retention of 91 % and superb safety in pGr||SPAN full cell. The present exploitation broadens the electrolyte choices of SPAN-based batteries and paves the way for future applications for these batteries.

Molecular Micellar Aggregate Electrolytes Enable Durable Electrochemical Proton Storage.

Proton electrochemistry holds eminent potential for developing high capacity and rate energy storage devices in the post-lithium era. However, the decomposition of water in acidic aqueous electrolytes causes electrode corrosion, leading to capacity fading. Herein, we report a judicious design of molecular micellar aggregates as non-aqueous electrolytes for stable and high-voltage electrochemical proton storage. The key to our strategy lies in introducing cetyltrimethylammonium bromide (CTAB), forming micelles to improve the miscibility of acetonitrile (ACN) and H3PO4, afford channel for proton transport, and electrostatically interact with phosphate ions of H3PO4 to further promote proton transport. Such aggregates impart rapid and stable electrochemical proton storage with a widened operating voltage (1.8 V vs. 1.5 V in aqueous electrolyte). By optimizing CTAB content, proton transport can be enhanced. Asymmetric full proton battery using the optimal CTAB electrolyte achieves a maximum energy density of 102.8 Wh kg-1 and a maximum power density of 10.1 kW kg-1. Our simple yet robust route to micellar aggregate electrolytes enables stable proton storage, underscoring its potential for grid-scale energy storage, emergency power supplies, and portable electronics.

Molecular Micellar Aggregate Electrolytes Enable Durable Electrochemical Proton Storage

Proton electrochemistry holds eminent potential for developing high capacity and rate energy storage devices in the post‐lithium era. However, the decomposition of water in acidic aqueous electrolytes causes electrode corrosion, leading to capacity fading. Herein, we report a judicious design of molecular micellar aggregates as non‐aqueous electrolytes for stable and high‐voltage electrochemical proton storage. The key to our strategy lies in introducing cetyltrimethylammonium bromide (CTAB), forming micelles to improve the miscibility of acetonitrile (ACN) and H3PO4, afford channel for proton transport, and electrostatically interact with phosphate ions of H3PO4 to further promote proton transport. Such aggregates impart rapid and stable electrochemical proton storage with a widened operating voltage (1.8 V vs. 1.5 V in aqueous electrolyte). By optimizing CTAB content, proton transport can be enhanced. Asymmetric full proton battery using the optimal CTAB electrolyte achieves a maximum energy density of 102.8 Wh kg‐1 and a maximum power density of 10.1 kW kg‐1. Our simple yet robust route to micellar aggregate electrolytes enables stable proton storage, underscoring its potential for grid‐scale energy storage, emergency power supplies, and portable electronics.

The Application of the Design of Experiments and Artificial Neural Networks in the Development of a Fast and Straightforward HPLC-UV Method for Fluconazole Determination in Hemato-Oncologic Pediatric Patients and Its Adaptation to Therapeutic Drug Monitoring.

Objectives: This study aimed to develop an optimized and wide concentration range HPLC-UV method for fluconazole (FLU) determination and its adaptation for pharmacokinetics (PK) studies in the pediatric population. Methods: The following parameters of chromatographic separation were optimized: retention time, tailing factor, peak height, and the sample preconditioning parameter, such as recovery. The optimization process involved the use of a central composite design (CCD) and Box-Behnken design (BBD) in the design of experiments (DoE) approach and a multilayer perceptron (MLP) for artificial neural network (ANN) application. Statistical and PK analyses were performed using Statistica and PKanalix. Results: The acetonitrile (ACN) concentration revealed the most significant factor influencing the retention time, tailing factor, and peak height of FLU and the internal standard. For recovery, the extracting agent's volume was the most significant factor. In most cases, the analysis conducted with the DoE and ANN indicated the same factors in a similar order regarding their impact on the analyzed variables. The optimization process allowed for achieving a wide range of determined concentrations (0.5-100 mg/L) and ~100% recovery. The developed method enabled PK analysis of 12 samples from three pediatric patients, proving its clinical usability. The estimated median clearance (CL) and volume of distribution (Vd) were 1.01 L/h and 18.64 L, respectively. Conclusions: DoE and ANNs are promising and useful tools in the optimization of sample preconditioning as well as the HPLC separation procedure. The investigated fluconazole determination method meets the European Medicines Agency (EMA) validation objectives and might be used in pediatric and adult PK studies.

Mechanistic Insights on Chemosensing Response of Pyrene and Anthracene Based Fluorescent Probes Towards Nitroaromatic Compounds.

Two polyaromatic hydrocarbon-based compounds, N2,N4,N6-tris-((pyren-1-yl)methyl)-1,3,5-triazine-2,4,6-triamine (SM1) and N2,N4,N6-tris-((anthracen-9-yl)methyl)-1,3,5-triazine-2,4,6-triamine (SM2) are explored as chemosensors for detecting nitroaromatic compounds. The chemosensing studies of SM1 and SM2 showed selective sensing of 4-nitroaniline (4NA) in homogeneous medium (in Acetonitrile (ACN) and in DMSO), which is due to the hyperpolarizability of 4NA. Quenching mechanism studied for the three analytes (4NA, 2NA and PA) showed dynamic quenching in SM1 in presence of 4NA and 2NA, while static quenching in presence of PA. Solvent effect on the chemosensing response of SM1 and SM2 towards PA was observed and it showed enhancement in the response on changing the solvent from ACN to DMSO to water. DFT studies, photophysical analysis, NMR experiments and complex synthesis experiments were done to provide in depth analysis on the observed sensing phenomena. Both SM1 and SM2 being insoluble in water, were used as heterogeneous chemosensors in aqueous medium, where selective sensing was observed for 4NA and PA. The LOD of PA and 4NA by SM1 in water was found to be 1.3 ppt and 2.1 ppt, respectively. The recyclability and stability after sensing studies were confirmed by PXRD.

Evaluation of Quercetin's Bioenhancing Effect on Oral Pharmacokinetics of Rosuvastatin in Wistar Rats Using RP-HPLC Method.

The absolute oral bioavailability of rosuvastatin (RST), a secondgeneration statin, is low i.e. 20% and only 10% is recovered as metabolite N-desmethy l rosuvistatin. Since it is a hydrophilic statin, RST relies on the organic anion transporting polypeptide- 1B1 (OATP-1B1), as the key mechanism for active transport into hepatocytes. Quercetin (QUE) being a bio enhancer and inhibitor of OATP1B1 can augment the bioavailability and pharmacokinetics of RST. The present study includes the development of a simple and validated bioanalytical Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) method for the estimation of RST and to study the effect of co-administration of QUE as a bio enhancer on its bioavailability. An analytical column of Kromasil 100, C18 (250 mm × 4.6 mm, 5 μm), was used for chromatographic separationand acetonitrile (ACN): acetic acid buffer pH 3.0 adjusted with glacial acetic acid (55:45 Vol. %) as mobile phase with flow rate 1.0 ml/min monitored at 242 nm. The ACN: methanol (50:50 Vol. %) was employed as the final solvent for extraction. The developed method has been successfully applied in a study on the pharmacokinetics of the drug RST in rats after co-administration of QUE, which was carried out using non-compartmental analysis in order to estimate the blood concentration of the drug. The pharmacokinetics of RST was found to be altered significantly (highest concentration of RST in the blood (Cmax) = 67.3 ng/ml to 122.2 ng/ml) (p < 0.001), area under curve (AUC)0-t (p < 0.0001) and AUC0-inf (p = 0.0005) when co-administered with QUE at 120 min (tmax). The results are in accordance with the fact that QUE increases plasma levels in rats through herb-drug interactions.

Multi‐walled carbon nanotubes co‐doped with sulfur and nitrogen as sensors for the simultaneous electrochemical determination of biomolecules

AbstractMulti-walled carbon nanotubes co-doped with sulfur and nitrogen (S–N-MWCNTs) were produced onto silicon/silicon oxide by means of chemical vapor deposition (CVD) upon decomposition of dimethyl sulfoxide (DMSO) and acetonitrile (ACN) in the presence of ferrocene (FeCp2). The synthesized S–N-MWCNTs were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and electrochemical impedance spectroscopy (EIS). The electrochemical response of S–N-MWCNTs towards oxidation of ascorbic acid (AA), dopamine (DA), uric acid (UA), and glucose (GL) was investigated in phosphate buffer solution (PBS) (pH 7.4) by means of cyclic voltammetry (CV). Strong dependence of electrochemical quality of S–N-MWCNTs on the concentration of decomposed DMSO precursor was observed. Namely, upon increasing the percentage of decayed DMSO from 1.0 up to 2.0% wt., the electrocatalytic activity of S–N-MWCNTs tends to improve. The separations of oxidation waves between AA-DA, DA-UA, and AA-UA reached their maximum values on S–N-MWCNTs-3, fabricated upon decomposition of 2.0% wt. DMSO precursor, permitting their individual and simultaneous electrochemical determination. Strong interference of GL in the analysis of DA was observed, and consequently, simultaneous analysis of AA, DA, and UA can be only carried out in the absence of GL. A great influence of concentration of decomposed DMSO precursor on the sensitivity of S–N-MWCNTs was also observed. Specifically, upon increasing the percentage of decayed DMSO from 1.0 up to 2.0% wt., the sensitivity and detection capability of S–N-MWCNTs towards AA, DA, UA, and GL analytes tend to enhance.

Implementation of phosphonium salt for high-performance supercapacitors from room to ultra-low temperature conditions

Conventional supercapacitors encounter limitations in operating voltage and performance at low temperatures due to poor ionic conductivity and diminished interfacial dynamics in electrolytes. In this study, we synthesized the phosphonium salt 5-phosphinaspiro[4.4] nonane tetrafluoroborate (PSNBF4) for the first time. We extensively characterized the physical and electrochemical properties of PSNBF4 in acetonitrile (AN) and propionitrile (PN) as electrolytes, assessing their performance in supercapacitors at room temperature and − 40 °C. The results demonstrate PSNBF4 electrolytes exhibit high solubility, outstanding ionic conductivity (1 M PSNBF4/AN: 49.8 mS cm−1; 1 M PSNBF4/PN: 27.5 mS cm−1), and high electrochemical stability, contributing to good capacitance retention after 500 h of floating tests at 25 °C. Supercapacitors using PSNBF4/AN retained 78 % of their capacitance at 3.1 V, whereas those with PSNBF4/PN maintained 68 % at 3.2 V. Impressively, these supercapacitors performed exceptionally well at −40 °C, displaying excellent cycle stability and high capacitance retention at elevated voltages. Supercapacitors with PSNBF4/AN retain 96.6 % of their capacitance at 3.2 V, while PSNBF4/PN retained 93.4 % of their capacitance at 3.4 V after floating for 500 h. These results demonstrate PSNBF4-based supercapacitors can operate effectively at high voltages in both room and extremely low temperatures, addressing a significant challenge in commercial supercapacitor applications.

Exploring the Formulation and Efficacy of Phosphazene-Based Flame Retardants for Conventional Supercapacitor Electrolytes.

The formulation of safe electrolytes for supercapacitors based on phosphazene used as a flame-retardant (FR) is carried out. 3 molecules are used: hexafluorocyclotriphosphazene (FR1), (ethoxy)pentafluorocyclotriphosphazene (FR2) and pentafluoro(phenoxy)cyclotriphosphazene (FR3). A comparative study on the efficacy from a safety point of view is performed to determine the minimum percentages of each to be used in a conventional acetonitrile (ACN)/1.0 M tetraethylammonium tetrafluoroborate (Et4NBF4) electrolyte to make it non-flammable. Flammability tests have shown that 5 %FR1, 15 %FR2 or 20 %FR3 are required to do that. The FTIR coupled to the TGA as well as the measurements of surface tensions and contact angles showed that the FRs tend to protect the surface of the electrolyte. The transport properties always remain good, superior to PC/1.0 M Et4NBF4 for example, and the electrochemical stability windows determined in 3-electrode cells with platinum or activated carbon are at least 2.5 V. The cycling performances are also interesting because the AC|AC EDLCs made in this study are compatible with these FRs, which makes it possible to operate devices providing energies and powers of 23.0 Wh kg-1 and 3.7 kW kg-1 with the electrolytes based on FR1 or FR2 between 0 and 2.5 V.

Thin and Flexible PANI/PMMA/CNF Forest Films Produced via a Two-Step Floating Catalyst Chemical Vapor Deposition.

In this paper, we explore a straightforward two-step method to produce high-purity, vertically aligned multi-walled carbon nanofibres (MWCNFs) via chemical vapor deposition (CVD). Two distinct solutions are utilized for this CVD method: a catalytic solution consisting of ferrocene and acetonitrile (ACN) and a carbon source solution with camphor and ACN. The vapors of the catalytic solution inserted in the reaction chamber through external boiling result in a floating catalyst CVD approach that produces vertically aligned CNFs in a consistent manner. CNFs are grown in a conventional CVD horizontal reactor at 850 °C under atmospheric pressure and characterized by Raman spectroscopy, scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Coating the MWCNTs with polymethyl methacrylate (PMMA) while still on the Si substrate retains the structure and results in a flexible, conductive thin film suitable for flexible electrodes. The film is 62 μm thick and stable in aqueous solutions, capable of withstanding further processing, such as electropolymerization with polyaniline, to be used for energy storage applications.

Temperature dependence of intraparticle diffusion of coumarin in single octadecylsilyl-functionalized silica particle revealed by fluorescence microspectroscopy

Abstract We explore the intraparticle diffusion of coumarin 102 (C102) in an octadecylsilyl-functionalized (ODS) silica particle in acetonitrile (ACN)/water and butanol (BuOH)/water systems at varying temperatures (T). The enthalpy-entropy compensation plots of the distribution coefficient of C102 in the ODS silica particle found that the distribution mechanism differed between ACN and BuOH. The T-dependent intraparticle diffusion coefficient (Dintra) of C102 in a single particle was determined with fluorescence microscpectroscopy using laser trapping and fluorescence recovery after photobleaching. The obtained Dintra was analyzed based on Arrhenius plots and the pore and surface diffusion model. As a result, we revealed that C102 transferred in the ODS silica particle in the ACN/water solution through only surface diffusion, while both pore and surface diffusions were observed in the BuOH/water solution. It was found that the formation of an interfacial liquid phase was the reason for the observed surface-only diffusion in the ACN system. This was supported by the activation energy of Dintra and surface diffusion coefficient. Moreover, we demonstrate for the first time that the proposed system allows the evaluation of T-dependence of Dintra in a single particle.

Retention behavior of Hg2+, MeHg+, thimerosal and phenylmercuric acetate on a C18 RP-HPLC column

Humans are exposed to potentially toxic mercuric mercury (Hg2+) and methylmercury (MeHg+) by the ingestion of food, to the bactericidal vaccine additive thimerosal (THI), and/or to the antifungal compound phenylmercuric acetate (PMA) which is used in some lens cleaning ophthalmic fluids. While numerous HPLC methods have been developed to separate Hg2+ and MeHg+ in environmental samples (e.g. food, surface waters), comparatively few have been reported for THI and PMA, in part owing to their increased hydrophobicity. We investigated the retention behavior of Hg2+, MeHg+, THI and PMA on a reversed-phase (RP) HPLC column using a flame atomic absorption spectrometer (FAAS) as a Hg-specific detector. Mobile phases comprised of 50 mM phosphate buffer (pH 7.4) with acetonitrile (ACN) concentrations of 30–50 % (v:v) produced single Hg-peaks, which eluted in the order THI, Hg2+, MeHg+ and PMA. With the 50 % ACN mobile phase, all mercurials eluted within 5 min. While the utilization of a FAAS precludes the analysis of environmental waters with the developed RP-HPLC-FAAS method, the latter is useful to probe the stability of THI and PMA in the presence of physiologically relevant concentrations of salt (100 mM in blood plasma) and l-cysteine (0.5 mM in hepatocyte cytosol), which is important as both mercurials have been recently shown to effectively inhibit the main protease of SARS-CoV-2, though the actual inhibitory Hg-species is unknown.

Enhancement of Charge Transfer Reaction at Electrode/Electrolyte Interface in Acetonitrile Solvent for Lithium-Ion Battery Cathode

High rate capability of Li-ion batteries for automotive battery applications is desired, which requires a reduction in internal resistance. Among the elementary reactions on Li-ion battery, the charge transfer resistance at electrode/electrolyte interface is known to be the rate-determined reaction1), which needs to be reduced to achieve the high-rate performance. The activation energy of the charge transfer at electrode/electrolyte interface depends on the donor number2) and the pre-exponential factor on the viscosity of electrolyte3). The use of acetonitrile (AN) solvent, which has relatively low viscosity and low donor number, as electrolyte solvent is expected to improve the high-rate performance. In this study, the effect of AN solvent on the charge transfer reaction at electrode/electrolyte interface is analyzed by electrochemical reaction analysis using the three-electrode cell with solid electrolyte, which enables AN to be used as the electrolyte solvent.Composite electrodes with LiCoO2: polyvinylidene fluoride: acetylene black in weight ratio of 8:1:1 was used as the working electrode, and lithium metal was used as the counter electrode and the reference electrode. In order to use AN as the electrolyte solvent, which is highly reactive with lithium metal, NASICON-type solid electrolyte Li1+x+y Al x (Ti2−y Ge y )P3−z Si z O12 was inserted between the working and counter electrodes, enabling the use of different liquid electrolytes on the working electrode side and the counter electrode side. Liquid electrolyte 1 M LiTFSI/Propylene Carbonate (PC) was used as the electrolyte on the counter electrode side, which is in contact with lithium metal, and three types of liquid electrolyte 1 M LiTFSI/AN, 1 M LiTFSI/PC and 1 M LiTFSI/ethylene carbonate: ethyl methyl carbonate (3:7 v/v%) (EC:EMC) were used as the electrolyte on the working electrode side, which is not in contact with lithium metal. After 10 hours from the cell preparation, two cycles of galvanostatic charge/discharge measurements at current rate of 0.1 C (cut off potential : 3.2 V-4.2 V vs. Li/Li+) were performed, followed by galvanostatic charge/discharge measurements at current rate of 0.1 C-0.5 C (cut off potential : 3.2 V-4.2 V vs. Li/Li+) and AC impedance measurements in measurement temperature range 268 K-298 K (measurement frequency :1 MHz-10 mHz, measurement potential : 4.0 V vs. Li/Li+, potential amplitude : 10 mV).The galvanostatic charge/discharge tests showed that the cells with PC and EC:EMC both exhibited a charge/discharge capacity of approximately 60 mAh g-1 at current rate of 0.25 C. On the other hand, the cell with AN exhibited a high charge/discharge capacity of 105 mAh g-1, indicating that the cell with AN maintains better reversible capacity under high current density conditions. AC impedance analysis showed no significant difference in the activation energy of the charge transfer at electrode/electrolyte interface among the three cells, although the reduction in the interfacial charge transfer resistance due to the increase in the pre-exponential factor was observed in the cell with AN. This can be explained by the use of low viscosity acetonitrile solvent, which increases the frequency of reorientation of solvent molecules during the solvation/desolvation processes3). This study confirms the high-rate performance of the cell with AN due to the increase in the pre-exponential factor rather than the reduction in the activation energy of the charge transfer at electrode/electrolyte interface.