Test of Various Photocathodes

A test of various photocathodes was carried out. The tested materials were CsI, CsTe, their multi-layers and so on. The quantum efficiencies of the various materials were measured under a vacuum and/or after exposure to several kinds of gases.Comment: 7 pages, Latex format(article), figures included, published in NIM A343(1994)11

Direct CP violation in three-body decays of the BB meson by resonance effects

We discuss direct CP violation in three-body decays of $B$ meson such as $B^\pm \to K^\pm\pi^+\pi^-$, which involves various intermediate resonance states, such as $B^\pm \to K^*_i \pi^\pm$ and $B^\pm \to \rho K^\pm$, where $K^*_i$ represents the $\pi K$ resonance. Due to the large final state interaction phases of the resonances, the CP asymmetry can be as large as the 25% level near the kinematical region where the $K^*_i$ and $\rho$ resonances overlap. By examining a Dalitz plot of this mode and combining a measurement of the branching ratio for $B^\pm \to \rho^\pm K$, it is possible to extract the weak phase, $\phi_3$= arg$(-V_{ud}V_{ub}^*/(V_{cd}V_{cb}^*))$, of the Kobayashi-Maskawa matrix.Comment: 12 pages, 1 figures. Argument to determine the CKM angle is changed. Also available via anonymous ftp at ftp://ftp.kek.jp/kek/preprints/TH/TH-54

The Albedo of Ryugu: Evidence for a High Organic Abundance, as Inferred from the Hayabusa2 Touchdown Maneuver

The Hayabusa2 mission successfully collected samples from the asteroid Ryugu last year and will return these to Earth in December 2020. It is anticipated that the samples will enable the analysis of terrestrially uncontaminated organic matter and minerals. Such analyses are in turn expected to elucidate the evolution of organic matter through Solar System history, including the origination and processing of biogenically important molecules, which could have been utilized by the first organisms on Earth. In anticipation, studies have made predictions concerning the properties of Ryugu, including its composition. The spectral characteristics of Ryugu, such as albedo, have been employed to relate the asteroid to members of the carbonaceous chondrite group that have been identified on Earth. However, the recent Hayabusa2 touchdown highlights a disparity between the color of surfaces of displaced platy fragments, indicating a brightening trend for the surface exposed to space compared to that facing into the body. Here we present a mass balance calculation with reference to data from the literature, which indicates that Ryugu may contain a significantly higher abundance of organic matter (likely >50%) than the currently most accepted meteorite analogues. A high organic content may result in high levels of extractable organic matter for the second touchdown site, where the spacecraft sampled freshly exposed material. However, high abundances of insoluble aromatic/graphitic rich organic matter may be present in the first touchdown site, which sampled the surface of Ryugu that had been exposed to space. Moreover, we suggest that the potentially high organic abundance and the rubble-pile nature of Ryugu may originate from the capture of rocky debris by a comet nucleus and subsequent water-organic-mineral interactions and sublimation of water ice

Vibrational spectroscopy analysis of ligand efficacy in human M₂ muscarinic acetylcholine receptor (M₂R)

振動分光法を駆使した薬剤効能測定法の開発 --アセチルコリン受容体を標的とした神経疾患の治療薬開発への期待--. 京都大学プレスリリース. 2021-12-01.The intrinsic efficacy of ligand binding to G protein-coupled receptors (GPCRs) reflects the ability of the ligand to differentially activate its receptor to cause a physiological effect. Here we use attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy to examine the ligand-dependent conformational changes in the human M₂ muscarinic acetylcholine receptor (M₂R)). We show that different ligands affect conformational alteration appearing at the C=O stretch of amide-I band in M2R. Notably, ATR-FTIR signals strongly correlated with G-protein activation levels in cells. Together, we propose that amide-I band serves as an infrared probe to distinguish the ligand efficacy in M₂R) and paves the path to rationally design ligands with varied efficacy towards the target GPCR

Identification and characterization of novel components of a Ca2+/calmodulin-dependent protein kinase cascade in HeLa cells

AbstractIn this report, we cloned a novel calmodulin-kinase (CaM-KIδ) from HeLa cells and characterized its activation mechanism. CaM-KIδ exhibits Ca2+/CaM-dependent activity that is enhanced (∼30-fold) in vitro by phosphorylation of its Thr180 by CaM-K kinase (CaM-KK)α, consistent with detection of CaM-KIδ-activating activity in HeLa cells. We also identified a novel CaM-KKβ isoform (CaM-KKβ-3) in HeLa cells whose activity was highly Ca2+/CaM-independent. Transiently expressed CaM-KIδ exhibited enhanced protein kinase activity in HeLa cells without ionomycin stimulation. This sustained activation of CaM-KIδ was completely abolished by Thr180Ala mutation and inhibited by CaM-KK inhibitor, STO-609, indicating a functional CaM-KK/CaM-KIδ cascade in HeLa cells

The Magnetic Phase of Lithium Transition Metal Phosphates LiMPO4 (M=Mn, Co, Ni) Detected by μ+SR

AbstractThe magnetic properties of the olivine-type compounds LiMPO4 (M = Mn, Co, Ni) are probed using muon spin rotation/relaxation (μSR). These materials pose an appealing magnetic structure and a high -potential technological interest as cathode materials for future rechargeable Li-ion batteries. The LiMPO4 family of compounds consists of a corner-sharing MO6 octahedra of high-spin M2+ ions manifesting an antiferromagnetic ground state below TN ≈ 30K. Additionally, these compounds belong to a class of materials exhibiting properties between two-and three dimensional systems. A comparative study between the family members is presented

Origin of ocean island basalts in the West African passive margin without mantle plume involvement

The geochemical variabilities in intraplate basalts (IB) from the West African passive margin (WAPM) region, have generally been employed to indicate the presence of recycled materials in an associated upwelling mantle plume. However, the absence of time-progressive linear hotspot tracks in WAPM-IB make it difficult to explain their genesis solely by the mantle plume hypothesis. Here, we show that the Sr–Nd–Hf–Pb isotopic variations in basalts from most of the WAPM-IB could have mainly attributed to the derivation from two types of fusible regions of the refertilized subcontinental lithospheric mantle (SCLM) and the sub-lithospheric mantle. The locations and magma genesis of WAPM-IB are strongly related to the distance from the Mesozoic rift axis and the structure of the rifted SCLM. The melting of the source region can possibly be attributed to small-scale mantle convection at the base of the SCLM without the involvement of a mantle plume

Brazilian Propolis Suppresses Angiogenesis by Inducing Apoptosis in Tube-Forming Endothelial Cells through Inactivation of Survival Signal ERK1/2

We recently reported that propolis suppresses tumor-induced angiogenesis through tube formation inhibition and apoptosis induction in endothelial cells. However, molecular mechanisms underlying such angiogenesis suppression by propolis have not been fully elucidated. The aim of this study was to investigate the effects of ethanol extract of Brazilian propolis (EEBP) on two major survival signals, extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt, and to elucidate whether changes in these signals were actually involved in antiangiogenic effects of the propolis. Detection by western blotting revealed that EEBP suppressed phosphorylation of ERK1/2, but not that of Akt. Pharmacological inhibition by U0126 demonstrated that ERK1/2 inactivation alone was enough to inhibit tube formation and induce apoptosis. It was also shown that EEBP and U0126 similarly induced activation of caspase-3 and cleavage of poly ADP-ribose polymerase (PARP) and lamin A/C, all of which are molecular markers of apoptosis. These results indicate that inhibition of survival signal ERK1/2, and subsequent induction of apoptosis, is a critical mechanism of angiogenesis suppression by EEBP