Iridium-Catalyzed Reductive (3+2) Annulation of Lactams Enabling the Rapid Total Synthesis of (±)-Eburnamonine.

A reductive (3+2) annulation of lactams through iridium-catalyzed hydrosilylation and photoredox coupling with α-bromoacetic acid was developed. The iridium-catalyzed hydrosilylation of the lactam carbonyl group and subsequent elimination provide a transient cyclic enamine, which undergoes iridium-catalyzed photoredox coupling with α-bromoacetic acid in a one-pot process. The developed conditions show high functional-group tolerance and provide cyclic N,O-acetals containing a quaternary carbon center. The resulting N,O-acetals undergo a variety of acid-mediated nucleophilic addition reactions via iminium ions to give substituted cyclic amines. The developed sequence including reductive (3+2) annulation and acid-mediated nucleophilic addition was successfully applied to the four-step total synthesis of (±)-eburnamonine.

Development of an imaging system for visualization of Ebola virus glycoprotein throughout the viral lifecycle.

Ebola virus (EBOV) causes severe EBOV disease (EVD) in humans and non-human primates. Currently, limited countermeasures are available, and the virus must be studied in biosafety level-4 (BSL-4) laboratories. EBOV glycoprotein (GP) is a single transmembrane protein responsible for entry into host cells and is the target of multiple approved drugs. However, the molecular mechanisms underlying the intracellular dynamics of GP during EBOV lifecycle are poorly understood. In this study, we developed a novel GP monitoring system using transcription- and replication-competent virus-like particles (trVLPs) that enables the modeling of the EBOV lifecycle under BSL-2 conditions. We constructed plasmids to generate trVLPs containing the coding sequence of EBOV GP, in which the mucin-like domain (MLD) was replaced with fluorescent proteins. The generated trVLP efficiently replicated over multiple generations was similar to the wild type trVLP. Furthermore, we confirmed that the novel trVLP system enabled real-time visualization of GP throughout the trVLP replication cycle and exhibited intracellular localization similar to that of wild type GP. In summary, this novel monitoring system for GP will enable the characterization of the molecular mechanism of the EBOV lifecycle and can be applied for the development of therapeutics against EVD.

Complex Photoconductivity Reveals How the Nonstoichiometric Sr/Ti Affects the Charge Dynamics of a SrTiO3 Photocatalyst.

Strontium titanate (SrTiO3) is a perovskite that is important in water-splitting photocatalytic chemistry. Although excess Sr is known to improve the photocatalytic activity, its effect on charge dynamics remain largely unaddressed. Herein, we present a detailed analyses of gigahertz complex transient photoconductivity (Δσ) measured using time-resolved microwave conductivity (TRMC). We show that charge carrier trapping associated with the emergence of an anomalous positive imaginary part and the first-order rate constant of the normal positive real part of Δσ dramatically decreased with increasing Sr/Ti ratio. The second-order rate constant attributed to charge recombination simultaneously decreased, and these rate constants were well correlated with the improved hydrogen evolution rate of aqueous SrTiO3 suspensions with a Pt co-catalyst. These findings provide a fresh perspective on the stoichiometry-carrier dynamics relationship paramount for the optimization of composition-engineered photocatalysts and reveal the broad implications for mechanistic studies based on TRMC evaluation.

Tube radial distribution chromatography system developed by combining commercially available HPLC system and open-tubular capillary tube as separation column.

Tube radial distribution chromatography based on tube radial distribution flow, or annular flow, in an open-tubular capillary has been reported, where the annular flow is created through phase separation multiphase flow. The chromatographic system requires some specific instruments and treatments for microfluidic flow in the capillary tube. In this study, we developed a new set-up for tube radial distribution chromatography by combining a commercially available HPLC system with an open-tubular capillary tube (with an inner diameter of 100 µm) as a separation column instead of a conventional packed column. The analyte solution was injected with an injection valve (2 µL volume) and a ternary solution of water/acetonitrile/ethyl acetate (3:8:2 vol ratio) was delivered as the eluent to the capillary tube at a flow rate of 8.6 µL min-1. The chromatographic system, that is, the HPLC system equipped with the open-tubular capillary tube, could successfully separate the model analytes, 1-naphthol, 1-naphthalenesulfonic acid, and 2,6-naphthalenedisulfonic acid, with base-line separation. The inner and outer phases in the annular flow worked as the mobile and pseudo-stationary phases, respectively, in the tube radial distribution chromatography system. The experimentally obtained elution times of the analytes were compared with their corresponding theoretical values calculated using their capacity factors for the inner and outer phases and the linear flow velocities of the respective phases.

Implementation of Tube Radial Distribution Chromatography by Using a Commercially Available HPLC System.

Tube radial distribution chromatography based on tube radial distribution flow, or annular flow, in an open-tubular capillary has been reported. The chromatographic system requires specific instruments and treatments for microfluidic flow in the capillary tube. In this study, we have developed a new model of tube radial distribution chromatography, which is comprised of a commercially available HPLC system without any packed separation columns. Separation is performed in an open-tubular pipe (100-µm inner diameter and 350-cm length; temperature, 5°C) connected between the pump and the detector in the HPLC system. An analyte solution is introduced with a sample injector (2-µL volume) and a ternary water/acetonitrile/ethyl acetate mixed solution (volume ratio of 3:8:2) is delivered as an eluent solution into the pipe at a flow rate of 10-µL min-1. Fused silica and stainless pipes can separate 1-naphthol and 2,6-naphthalenedisulfonic acid, but a polyetheretherketone pipe cannot. The obtained data provides an important clue to practical developments in separation science.

[Dual process in large number estimation under uncertainty].

According to dual process theory, there are two systems in the mind: an intuitive and automatic System 1 and a logical and effortful System 2. While many previous studies about number estimation have focused on simple heuristics and automatic processes, the deliberative System 2 process has not been sufficiently studied. This study focused on the System 2 process for large number estimation. First, we described an estimation process based on participants' verbal reports. The task, corresponding to the problem-solving process, consisted of creating subgoals, retrieving values, and applying operations. Second, we investigated the influence of such deliberative process by System 2 on intuitive estimation by System 1, using anchoring effects. The results of the experiment showed that the System 2 process could mitigate anchoring effects.