Reaction Mechanism of Hydrogen Evolution over MoS2 : Tafel vs. Heyrovsky

Molybdenum disulfide (MoS2)-based materials have emerged as promising catalysts for hydrogen evolution reaction (HER). However, the reaction mechanism has been still questionable as such whether HER follows Volmer-Tafel or Volmer-Heyrovsky routes. In this work, we aim to settle the controversial issue by clearly describing the thermodynamic predominance of one type mechanism over the other via the density functional theory calculation. In order to describe the solid-electrolyte interface, the periodic MoS2 slabs and explicit solvated protons were initially modeled with implicit water environment. Subsequently, by varying the number of solvated protons in the electrolyte layer, the reaction energetics and activation barriers were investigated as a function of electrode potential, which was determined by the work-function calculation. By comparing the free energy barrier at the rate-determining step of each reaction, we found that Volmer-Heyrovsky mechanism is predominant in the HER. In addition, to study the size-dependent HER activity, the reaction barriers of monolayer and bulk MoS2 were also investigated. These fundamental understandings into the underlying mechanism and size effects in the HER will surely help the design of advanced HER catalysts

Ursodeoxycholic acid may protect from severe acute respiratory syndrome coronavirus 2 Omicron variant by reducing angiotensin‐converting enzyme 2

Abstract The SARS‐CoV‐2 caused COVID‐19 pandemic has posed a global health hazard. While some vaccines have been developed, protection against viral infection is not perfect because of the urgent approval process and the emergence of mutant SARS‐CoV‐2 variants. Here, we employed UDCA as an FXR antagonist to regulate ACE2 expression, which is one of the key pathways activated by SARS‐CoV‐2 Delta variant infection. UDCA is a well‐known reagent of liver health supplements and the only clinically approved bile acid. In this paper, we investigated the protective efficacy of UDCA on Omicron variation, since it has previously been verified for protection against Delta variant. When co‐housing with an Omicron variant‐infected hamster group resulted in spontaneous airborne transmission, the UDCA pre‐supplied group was protected from weight loss relative to the non‐treated group at 4 days post‐infection by more than 5%–10%. Furthermore, UDCA‐treated groups had a 3‐fold decrease in ACE2 expression in nasal cavities, as well as reduced viral expressing genes in the respiratory tract. Here, the data show that the UDCA serves an alternative option for preventive drug, providing SARS‐CoV‐2 protection against not only Delta but also Omicron variant. Our results of this study will help to propose drug‐repositioning of UDCA from liver health supplement to preventive drug of SARS‐CoV‐2 infection

Highly Sensitive and Selective Liquid-Phase Sensors Based on a Solvent-Resistant Semiconducting Layers

Sensors based on organic field-effect transistor (OFETs) platform have attracted great interest owing to their high potentials in light-weight, flexibility, and large area electronics. However, organic semiconductors have critical drawback to become a ???practical??? sensor; poor resistance of organic semiconductors in common organic solvents. For this drawback, OFET-based sensors have been only demonstrated with vapor- and aqueous-phase analytes. Herein, we demonstrate the highly sensitive and selective OFET-based sensors based on solvent-resistant semiconducting layers. The cross-linked P3HT-azide copolymer has been introduced to increase the chemical resistance of the devices toward organic solvents. Various sensing demonstration were conducted by using various liquid-phase organic solvents and pH solutions

Safety Evaluation and Population Pharmacokinetics of Camostat Mesylate and Its Major Metabolites Using a Phase I Study

Camostat mesylate is expected to be promising as a treatment option for COVID-19, in addition to other indications for which it is currently used. Furthermore, in vitro experiments have confirmed the potential of camostat and its metabolites to be effective against COVID-19. Therefore, clinical trials were conducted to evaluate the safety and pharmacokinetic characteristics of camostat after single-dose administration. Additionally, we aim to predict the pharmacokinetics of repeated dosing through modeling and simulation based on clinical trials. Clinical trials were conducted on healthy Korean adults, and an analysis was carried out of the metabolites of camostat, GBPA, and GBA. Pharmacokinetic modeling and simulation were performed using Monolix. There were no safety issues (AEs, physical examinations, clinical laboratory tests, vital sign measurements, and ECG) during the clinical trial. The pharmacokinetic characteristics at various doses were identified. It was confirmed that AUC last and Cmax increased in proportion to dose in both GBPA and GBA, and linearity was also confirmed in log-transformed power model regression. Additionally, the accumulation index was predicted (1.12 and 1.08 for GBPA and GBA). The pharmacokinetics of camostat for various dose administrations and indications can be predicted prior to clinical trials using the developed camostat model. Furthermore, it can be used for various indications by connecting it with pharmacodynamic information

Development of ropivacaine hydrochloride-loaded dissolving microneedles as a local anesthetic agent: A proof-of-concept

Ropivacaine hydrochloride (RPL) is a local anesthetic agent that has been widely used for the treatment of pain during or after surgery. However, this drug is only available in parenteral dosage form and may contribute to the infiltration of RPL into the plasma, causing some undesirable side effects. Intradermal delivery of RPL using dissolving microneedles may become a promising strategy to deliver such drugs into the skin. This research aimed to develop RPL-loaded dissolving microneedles (DMN-RPLs) as a proof of the concept of intradermal delivery of a local anesthetic. The DMN-RPLs were fabricated using either centrifugation or air-pressurized chamber methods. Several polymers, such as poly(vinyl pyrrolidone) (PVP), poly(vinyl alcohol) (PVA), and sodium hyaluronate (SH), were utilized for manufacturing the DMN-RPLs. The prepared DMN-RPLs were assessed for their thermal properties, chemical bonds, mechanical strength, insertion ability, skin-dissolution study, and drug content. Furthermore, in-skin deposition and dermatokinetic studies were also performed. The results showed that F9 (30 % w/w PVP-4 % w/w SH) and F10 (30 % w/w PVP-5 % w/w PVA) containing 5 % w/w of RPL were the most promising formulations, as shown by their needle height reduction (&lt;10 %) and insertion depth (∼400 μm). Both formulations were also able to deliver more than 60 % of the RPL contained in the DMNs into the epidermis, dermis, and receiver compartment. This study, for the first time, has provided a proof concept to deliver RPL as a local anesthetic using DMNs and the intradermal route, aiming to minimize pain and discomfort during administration and improve the patient's experience.</p