NMR study in the superconducting silicon clathrate compound NaxBaySi46

29Si, 23Na, 137Ba, and 135Ba NMR experiments were carried out in the superconducting silicon clathrate compound NaxBaySi46 to study the electronic states above the superconducting transition temperature. We observed three distinct 29Si signals with different Knight shift (2036, 862, and 720 ppm at 90 K with a small temperature dependence of ∼10%), which were ascribed to inequivalent Si sites in the Si46 structure. The results indicate that the conduction-electron spin and/or charge density is strongly site-dependent. At all the atomic sites, the Korringa relation in NMR relaxation was observed, indicative of metallic electronic structure with moderate electronic correlation. The Na and Ba atoms are partially ionized in NaxBaySi46, which shows the noticeable difference from the system of alkali-metal-doped fullerides. The comparison with band calculations is discussed

High-pressure Raman study of the Ba-doped silicon clathrate Ba 24Si100 up to 27 GPa

High-pressure Raman scattering of type-III silicon clathrate Ba 24Si100 has been measured up to 27 GPa at room temperature. Low-frequency vibrational modes associated with Ba atoms inside three kinds of cages were found around 45-90 cm-1. The Si framework Raman bands were observed around 115-415 cm-1, which are altogether shifted toward lower frequencies as compared to those of type-I Ba 8Si46. High-pressure phase transition occurs at 6.5 GPa, which seems to be due to the structural distortion induced by the increasing guest(Ba)-host(Si) couplings. Ba24Si100 becomes irreversibly amorphous above 23 GPa. This pressure is lower than those of type-I Si clathrates, which suggests that type-III structure is less stable than type-I under high pressures

High-pressure Raman study of the iodine-doped silicon clathrate I8Si44I2

Raman scattering measurements of an iodine-doped I8Si44I2 clathrate have been performed at pressures up to 28 GPa and 296 K. We found two Raman peaks at 75 and 101 cm-1 associated with the vibrations of guest I atoms inside the host Si cages, and observed some framework vibrations around 120–500 cm-1. These characteristic Raman bands and their pressure dependence are investigated in consideration of our recent Ba8Si46 studies. The lowest-frequency framework vibration at 133 cm-1 shows the softening with pressure, which seems to be the common feature of Si clathrates. A strong and broad Raman band centered at 461 cm-1 is identified to the highest-frequency framework vibration, which is likely intensified and broadened by the considerable framework distortion due to the replacement of framework Si with larger I atom. No obvious pressure-induced phase transition was found up to 28 GPa. The guest-host interactions are investigated by the present vibrational properties and are compared with those of previous neutron studies of I8Si44I2

A new approach for measuring the muon anomalous magnetic moment and electric dipole moment

This paper introduces a new approach to measure the muon magnetic moment anomaly a?? = (g - 2)/2 and the muon electric dipole moment (EDM) d?? at the J-PARC muon facility. The goal of our experiment is to measure a?? and d?? using an independent method with a factor of 10 lower muon momentum, and a factor of 20 smaller diameter storage-ring solenoid compared with previous and ongoing muon g - 2 experiments with unprecedented quality of the storage magnetic field. Additional significant differences from the present experimental method include a factor of 1000 smaller transverse emittance of the muon beam (reaccelerated thermal muon beam), its efficient vertical injection into the solenoid, and tracking each decay positron from muon decay to obtain its momentum vector. The precision goal for a?? is a statistical uncertainty of 450 parts per billion (ppb), similar to the present experimental uncertainty, and a systematic uncertainty less than 70 ppb. The goal for EDM is a sensitivity of 1.5 ?? 10-21 ecm

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

Seasonal changes in the net radiation/solar radiation ratio above a Cryptomeria japonica plantation forest

The Priestley-Taylor (PT) equation requires net radiation Rn as input. Rn is often unavailable from many meteorological datasets. Rn may be estimated from downward solar radiation S↓ assuming Rn/S↓ values. We examined seasonal changes of Rn/S↓ values using 1-year radiation data observed above a coniferous evergreen plantation forest of Cryptomeria japonica. Rn/S↓ showed slight seasonal changes; however, other terms in the PT equation showed large seasonal changes. Thus, we conclude that assuming constant Rn/S↓ for all seasons is valid for this sitePriestley-Taylor 式（PT式）は純放射量Rnの入力を必要とする。しかし，Rnは気象データセットに含まれていないことが多い。Rnがデータセットから得られない場合，Rnと下向き日射量S↓の比を仮定することで，RnをS↓ から推定するという方法が考えられる。本研究では，スギ人工林上で計測されたRnとS↓ のデータから，Rn/S↓ の季節変化を調べた。Rn/S↓ はわずかに季節変化を示したが，その季節変化はPT式のほかの項の季節変化に比べて小さかった。したがって，Rn/S↓を季節によらず一定と仮定することは，本研究の対象とした試験地において妥当であると結論され