Proceedings of the Japan Academy. Series B, Physical and Biological Sciences最新文献

Magnetron production and use far exceed that of other microwave tubes due to their high operational efficiency, power efficiency, and cost-effectiveness in production. The magnetron was named by A. W. Hull; however, the device invented by Hull differs from the magnetron utilized as a microwave tube. The magnetron widely used today is based on the split-anode magnetron invented by K. Okabe. This overview introduces two papers published by Okabe in the Proceedings of the Imperial Academy and discusses the events that led to the discovery of the split-anode magnetron. In addition, the operation mechanisms of magnetrons are explained.

Carbon nanotubes are a telecom band emitter compatible with silicon photonics, and when coupled to microcavities, they present opportunities for exploiting quantum electrodynamical effects. Microdisk resonators demonstrate the feasibility of integration into the silicon platform. Efficient coupling is achieved using photonic crystal air-mode nanobeam cavities. The molecular screening effect on nanotube emission allows for spectral tuning of the coupling. The Purcell effect of the coupled cavity-exciton system reveals near-unity radiative quantum efficiencies of the excitons in carbon nanotubes.

Flavonoids, such as quercetin and kaempferol, and their glycosides, are widely distributed in vegetables and fruits. Sugimura, T. et al. investigated the mutagenicity of flavone derivatives, and found that quercetin and kaempferol showed high mutagenic activities in Salmonella typhimurium TA98 with S9 mix, comparable to that of the typical carcinogen, benzo[a]pyrene. These novel findings were published in Proc. Jpn. Acad. Ser. B 53, 194-197, 1977. Other research groups also reported the mutagenic properties of flavone derivatives in S. typhimurium strains. These observations led to the commencement of long-term animal carcinogenesis experiments involving quercetin. A USA-Turkey joint study reported that feeding rats with 0.1% quercetin in the diet produced carcinomas. However, Japanese scientists showed no carcinogenicity with quercetin in rats, mice, or hamsters, even at 10% in the diet. NTP Technical Report on the Toxicology and Carcinogenesis Studies of Quercetin in F344/N Rats concluded that there was no evidence of its carcinogenic activity. Therefore, the potential risk of quercetin in human cancers is likely to be negligible. These flavonoid issues provided a warning regarding the simplistic understanding that mutagens are carcinogens, and microbial tests alone are inadequate for safety assessment; therefore, and a battery of tests for genotoxicity is recommended. Thus, the informative report in 1977 made significant contributions to initiating and promoting genotoxicity studies of flavonoids.

The chemical characterization of the heaviest elements at the farthest reach of the periodic table (PT) and the classification of these elements in the PT are undoubtedly crucial and challenging subjects in chemical and physical sciences. The elucidation of the influence of relativistic effects on their outermost electronic configuration is also a critical and fascinating aspect. However, the heaviest elements with atomic numbers Z ≳ 100 must be produced at accelerators using nuclear reactions of heavy ions and target materials. Therefore, production rates for these elements are low, and their half-lives are as short as a few seconds to a few minutes; they are usually available in a quantity of only a few atoms at a time. Here, we review some highlighted studies on heavy actinide and light transactinide chemical characterization performed at the Japan Atomic Energy Agency tandem accelerator facility. We discuss briefly the prospects for future studies of the heaviest elements.

Changes in expression levels of drug efflux pump genes, mexB and mexY, and porin gene oprD in Pseudomonas aeruginosa were investigated in this study. Fifty-five multidrug-resistant P. aeruginosa (MDRP) strains were compared with 26 drug-sensitive strains and 21 strains resistant to a single antibiotic. The effect of the efflux inhibitor Phe-Arg-β-naphthylamide on drug susceptibility was determined, and gene expression was quantified using real-time quantitative real-time reverse transcription polymerase chain reaction. In addition, the levels of metallo-β-lactamase (MBL) and 6'-N-aminoglycoside acetyltransferase [AAC(6')-Iae] were investigated. Efflux pump inhibitor treatment increased the sensitivity to ciprofloxacin, aztreonam, and imipenem in 71%, 73%, and 29% of MDRPs, respectively. MBL and AAC(6')-Iae were detected in 38 (69%) and 34 (62%) MDRP strains, respectively. Meanwhile, 76% of MDRP strains exhibited more than 8-fold higher mexY expression than the reference strain PAO1. Furthermore, 69% of MDRP strains expressed oprD at levels less than 0.01-fold of those in PAO1. These findings indicated that efflux pump inhibitors in combination with ciprofloxacin or aztreonam might aid in treating MDRP infections.

Significant progress has been achieved in the field of solid-state biosensors over the past 50 years. Various sensing devices with high-density integration and flexible configuration, as well as new applications for clinical diagnosis and healthcare, have been developed using blood, serum, and other body fluids such as sweat, tears, and saliva. A high-density array of ion-sensitive field effect transistors was developed by exploiting the advantages of advanced semiconductor technologies and commercialized in combination with an enzymatic primer extension reaction as a DNA sequencer in 2011. Different types of materials such as inorganic materials, metals, polymers, and biomolecules are mixed together on the surface of the gate while maintaining their own functions; therefore, compatibility among different materials has to be optimized so that the best detection performance of solid-state biosensors, including stability and reliability, is achieved as designed. Solid-state biosensors are suitable for the rapid, cost-effective, and noninvasive identification of biomarkers at various timepoints over the course of a disease.

This review describes the development of evolutionary studies of sex based on the volvocine lineage of green algae, which was facilitated by whole-genome analyses of both model and non-model species. Volvocine algae, which include Chlamydomonas and Volvox species, have long been considered a model group for experimental studies investigating the evolution of sex. Thus, whole-genomic information on the sex-determining regions of volvocine algal sex chromosomes has been sought to elucidate the molecular genetic basis of sex evolution. By 2010, whole genomes were published for two model species in this group, Chlamydomonas reinhardtii and Volvox carteri. Recent improvements in sequencing technology, particularly next-generation sequencing, allowed our studies to obtain complete genomes for non-model, but evolutionary important, volvocine algal species. These genomes have provided critical details about sex-determining regions that will contribute to our understanding of the diversity and evolution of sex.

Biomimetic molecular designs can yield superior biomaterials. Polymers with a phosphorylcholine group, a polar group of phospholipid molecules, are particularly interesting. A methacrylate monomer, 2-methacryloyloxyethyl phosphorylcholine (MPC), was developed using efficient synthetic reactions and purification techniques. This process has been applied in industrial production to supply MPC globally. Polymers with various structures can be readily synthesized using MPC and their properties have been studied. The MPC polymer surface has a highly hydrated structure in biological conditions, leading to the prevention of adsorption of proteins and lipid molecules, adhesion of cells, and inhibition of bacterial adhesion and biofilm formation. Additionally, it provides an extremely lubricious surface. MPC polymers are used in various applications and can be stably immobilized on material surfaces such as metals and ceramics and polymers such as elastomers. They are also stable under sterilization and in vivo conditions. This makes them ideal for application in the surface treatment of various medical devices, including artificial organs, implanted in humans.

The current understanding of the mechanism of core-collapse supernovae (CCSNe), one of the most energetic events in the universe associated with the death of massive stars and the main formation channel of compact objects such as neutron stars and black holes, is reviewed for broad readers from different disciplines of science who may not be familiar with the object. Therefore, we emphasize the physical aspects than the results of individual model simulations, although large-scale high-fidelity simulations have played the most important roles in the progress we have witnessed in the past few decades. It is now believed that neutrinos are the most important agent in producing the commonest type of CCSNe. The so-called neutrino-heating mechanism will be the focus of this review and its crucial ingredients in micro- and macrophysics and in numerics will be explained one by one. We will also try to elucidate the remaining issues.

In 1932, Mizushima and Higasi reported the dependence of the dipole moments of 1,2-dichloroethane on both temperature and solvent in the Proceedings of the Imperial Academy, Japan. This report was followed by their first proposal of the existence of conformers that exchanged by internal rotation about a C-C single bond based on experimental data. Their monumental work marked the beginning of the essential concept of conformation in modern stereochemistry. Their proposal was later confirmed by the direct observation of the anti and gauche conformers of 1,2-dichloroethane by Raman spectroscopy, and further supported by other experimental and theoretical methods. The relative stabilities of the anti and gauche conformers of 1,2-dichloroethane and other 1,2-disubstituted ethanes were discussed in terms of steric, electrostatic, and stereoelectronic effects based on analysis of calculated data. Those studies influenced the development of subsequent research in organic chemistry, such as the conformational analysis of cyclohexane derivatives and the isolation of chiral gauche conformers.