Total Colorimetric Evaluation of a Set of Color Sensors for a Variety of Illuminants and Objects

Recently, a new colorimetric evaluation model for a set of color sensors was proposed by the author (N. Shimano: J. Inst. Image Electron. Eng. Jpn. 29 (2000) 506 and 517.), and the quality was shown to be defined by the ratio of the statistical mean energy of color stimuli at the retina (SMECS) to the captured energy of the SMECS by the sensors. It was also shown that the quality depends on the illuminants and objects. The experimental results agreed quite well with the proposed model. However, an extension of the model is needed to evaluate the full colorimetric quality of an image acquisition device for a variety of illuminants and objects. In this paper the extended model called the total colorimetric quality model and experimental results for sensors under such a variety are presented.     

Energy‐resolved mass spectrometry for differentiation of the fluorine substitution position on the phenyl ring of fluoromethcathinones

A reliable method for structural analysis is crucial for the forensic investigation of new psychoactive substances (NPSs). Towards this end, mass spectrometry is one of the most efficient and facile methods for the identification of NPSs. However, the differentiation among 2‐, 3‐, and 4‐fluoromethcathinones (o‐, m‐, and p‐FMCs), which are ring‐fluorinated positional isomers part of the major class of NPSs referred to as synthetic cathinones, remains a challenge. This is mostly due to their similar retention properties and nearly identical full scan mass spectra, which hinder their identification. In this study, we describe a novel and practical method for differentiating the fluorine substitution position on the phenyl ring of FMCs, based on energy‐resolved mass spectrometry (ERMS) using an electron ionization‐triple quadrupole mass spectrometer. ERMS measurements showed that the three FMC positional isomers exhibited differences in relative abundances of both the fluorophenyl cation (m/z 95) and the fluorobenzoyl cation (m/z 123). The logarithmic plots of the abundance ratio of these two cations (m/z 95 to m/z 123) as a function of the collision energy (CE) followed the order of o‐FMC < p‐FMC < m‐FMC at each CE, which allowed the three isomers to be unambiguously and reliably differentiated. The theoretical dissociation energy calculations confirmed the relationship obtained by ERMS analyses, and additional ERMS measurements of methylmethcathinone positional isomers showed that the differences in abundance among the FMCs were attributed to the differences in their collision‐induced dissociation reactivities arising from the halogen‐induced resonance effects on the phenyl ring. Moreover, the method for differentiation described herein was successfully applied to the actual samples containing seized drugs. We expect that the described methodology will also contribute significantly to the reliable and accurate structural identification of NPSs in the fields of therapeutic, clinical, and forensic toxicology.     

Palladium-catalyzed Mizoroki-Heck reactions in water using thermoresponsive polymer micelles

Palladium-catalyzed Mizoroki-Heck reactions were carried out in water using thermoresponsive polymer micelles. The micelles were generated from thermoresponsive block copolymers consisting of a poly(N-isopropylacrylamide) (PNIPAAm) segment and a hydrophilic segment such as nonionic poly(ethylene glycol) (PEG) (2) and anionic poly(sodium p-styrenesulfonate) (PSSNa) (9). These copolymers exhibited lower critical solution temperature (LCST) behavior at ca. 40–50?°C and showed thermal stimuli-induced formation and dissociation of micelles. The copolymers formed micelles in aqueous solution at higher temperature, where catalytic reactions proceeded. At lower temperature, the micelles dissociated to form a clear solution, enabling efficient extraction of the products from aqueous reaction mixture. In the presence of these copolymers, palladium complexes catalyzed the coupling reactions between aryl iodides and alkene compounds inside the hydrophobic micelle cores in water under relatively milder conditions. Extraction of the products from the aqueous solution of 2 or 9 was found to be efficient enough in comparison with conventional surfactants.     

First asymmetric enantioselective total synthesis of phenanthridine alkaloid, (S)-(+)-asiaticumine and its enantiomer

In this study, the first asymmetric enantioselective total syntheses of (+)-asiaticumine A (2) and its enantiomer were accomplished through a seven-step sequence using the bond formation between the C4a and N5 positions of the phenanthridine framework based on the microwave-assisted electrocyclization of cyclohexenylbenzaldoxime methyl ether as an aza 6π-hexatriene system followed by the Sharpless asymmetric dihydroxylation as the key step. In addition, the absolute configuration of natural (+)-2 was determined to be S by Mosher’s method.     

A molecular dynamics study of free energy of micelle formation for sodium dodecyl sulfate in water and its size distribution

Free energy of micelle formation has been evaluated for spherical sodium dodecyl sulfate (SDS) in water by a thermodynamic integration method combined with a series of large-scale molecular dynamics calculations following the chemical species model. In particular, free energy change delta mu(n+1)0 with respect to the addition of one surfactant molecule to the spherical micelle of size n was obtained as a function of n. The free energy profile showed a minimum followed by a maximum, which corresponds to a peak in the size distribution. The calculated peak size n = 57 near its critical micelle concentration is in good agreement with the experimental averaged aggregation number n = 55-75 of the SDS micelle. The distribution showed a rather sharp peak, indicating that the size is almost a monodisperse one. The size is likely to be insensitive to the total concentration of the surfactant.     

Structure elucidation of cyasterone stereoisomers isolated from Cyathula officinalis

Chemical investigation of ecdysteroidal constituents of the roots and stems of Cyathula officinalis led to the isolation of two cyasterone stereoisomers, 2 and 3, together with the known cyasterone 1. The structures of compounds 2 and 3 were determined to be 28-epi-cyasterone and 25-epi-28-epi-cyasterone, respectively, by means of spectroscopic analysis. X-Ray structures of 1 and 2 confirmed the 24S,25S,28R configuration for 1 and 24S,25S,28S for 2.     

Benzimidazole-5-sulfonamides as novel nonpeptide luteinizing hormone releasing hormone (LHRH) antagonists: minimization of mechanism-based CYP3A4 inhibition

Herein we report the development of novel, potent and non-peptide luteinizing hormone releasing hormone (LHRH) antagonists. The optimization towards derivatives free from mechanism-based CYP3A4 inhibition is described. The identification of a main metabolite guided us towards structural modifications of the benzyl moiety, which resulted in significant improvements of the CYP3A4 profile, while maintaining potent LHRH antagonist activity.     

Supercurrent through hybrid junctions with anisotropic Cooper-pair condensates

A general formula for the supercurrent between different internal structures in a wide class of hybrid junctions is derived on the basis of the Andreev-reflection picture. The formula extends existing formulas and also enables us to analyze novel B-phase/A-phase/B-phase junctions in superfluid 3He systems. We propose a mechanism for pi states due to the (circumflex)l texture in the A phase of the junction, which could elucidate major features of the pi states with higher critical current ( H states) discovered in superfluid 3He weak links. The bistability of the pi states is also discussed.