655 research outputs found

    Oscillation Phenomena in the disk around the massive black hole Sagittarius A*

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    We report the detection of radio QPOs with structure changes using the Very Long Baseline Array (VLBA) at 43 GHz. We found conspicuous patterned changes of the structure with P = 16.8 +- 1.4, 22.2 +- 1.4, 31.2 +- 1.5, 56.4 +- 6 min, very roughly in a 3:4:6:10 ratio. The first two periods show a rotating one-arm structure, while the P = 31.4 min shows a rotating 3-arm structure, as if viewed edge-on. At the central 50 microasec the P = 56.4 min period shows a double amplitude variation of those in its surroundings. Spatial distributions of the oscillation periods suggest that the disk of SgrA* is roughly edge-on, rotating around an axis with PA = -10 degree. Presumably, the observed VLBI images of SgrA* at 43 GHz retain several features of the black hole accretion disk of SgrA* in spite of being obscured and broadened by scattering of surrounding plasma.Comment: 24 pages, 20 figures, revised version submitted to MN main journal (2010, Jan., 12th

    Magnetization Curves of the Reentrant-Spin-Glass Fe_<0.65>Mn_<0.35>TiO_3 : Dependence on the Sweep Rate of Magnetic Fields(Magnetism)

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    The magnetization curves of the reentrant-spin-glass Fe_Mn_TiO_3 have been observed at 4.2 K and 1.4 K in applied fields with various sweep rates. Depending on the sweep rates and temperatures, the anomalous jumps of the magnetizations towards the values of the field-cooled-magnetization M^ are observed. This phenomenon is interpreted to be closely related to the properties of the spin-glass state

    A novel cell adhesive protein engineered by insertion of the Arg-Gly-Asp-Ser tetrapeptide

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    This research was originally published in the Journal of Biological Chemistry. T Maeda, R Oyama, K Ichihara-Tanaka, F Kimizuka, I Kato, K Titani and K Sekiguchi. A novel cell adhesive protein engineered by insertion of the Arg-Gly-Asp-Ser tetrapeptide. J. Biol. Chem. 1989; 264: 15165-15168 © the American Society for Biochemistry and Molecular Biolog

    Serum REIC/Dickkopf-3 Protein Level Predicts Disease-Free Survival in Patients with Hepatocellular Carcinoma

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    The physiological role of the reduced expression of immortalized cells (REIC)/Dickkopf-3 (Dkk-3) protein in patients with hepatocellular carcinoma (HCC) remains unclear. In this study, we evaluated the effect of the REIC/Dkk-3 protein on HCC cell proliferation and assessed the relationship between the serum REIC/Dkk-3 protein level and the prognosis in patients with HCC. We evaluated the REIC/Dkk-3 protein-induced anticancer effects on Huh7 and Hep3B cells (HCC cell lines) in the presence of peripheral blood mononuclear cells (PBMCs), and found that combination treatment with REIC/Dkk-3 protein and PBMCs reduced the proliferation of HCC cells (Hep3B: 82.0%±16.3%; Huh7: 72.6%±9.1%). We also studied 194 HCC patients who underwent primary liver resection or primary radiofrequency ablation from 2008 to 2017. Serum REIC/Dkk-3 protein levels were measured by an enzyme-linked immunosorbent assay and compared to the prognostic data. The 3-year disease-free survival of the REIC/Dkk-3 high group was significantly higher than that in the REIC/Dkk-3 low group. In conclusion, this is the first study investigating the relationship between HCC patient survival and serum REIC/Dkk-3 protein levels in a large population. Based on the results, the serum REIC/Dkk-3 protein level should be considered a new prognostic marker for patients with HCC

    Crystal structure of CmABCB1 multi-drug exporter in lipidic mesophase revealed by LCP-SFX

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    がんの多剤排出の原因となっているABCトランスポーターの立体構造をSACLAのX線自由電子レーザーを用いて決定. 京都大学プレスリリース. 2021-12-23.CmABCB1 is a Cyanidioschyzon merolae homolog of human ABCB1, a well known ATP-binding cassette (ABC) transporter responsible for multi-drug resistance in various cancers. Three-dimensional structures of ABCB1 homologs have revealed the snapshots of inward- and outward-facing states of the transporters in action. However, sufficient information to establish the sequential movements of the open–close cycles of the alternating-access model is still lacking. Serial femtosecond crystallography (SFX) using X-ray free-electron lasers has proven its worth in determining novel structures and recording sequential conformational changes of proteins at room temperature, especially for medically important membrane proteins, but it has never been applied to ABC transporters. In this study, 7.7 mono­acyl­glycerol with cholesterol as the host lipid was used and obtained well diffracting microcrystals of the 130 kDa CmABCB1 dimer. Successful SFX experiments were performed by adjusting the viscosity of the crystal suspension of the sponge phase with hy­droxy­propyl methyl­cellulose and using the high-viscosity sample injector for data collection at the SACLA beamline. An outward-facing structure of CmABCB1 at a maximum resolution of 2.22 Å is reported, determined by SFX experiments with crystals formed in the lipidic cubic phase (LCP-SFX), which has never been applied to ABC transporters. In the type I crystal, CmABCB1 dimers interact with adjacent molecules via not only the nucleotide-binding domains but also the transmembrane domains (TMDs); such an interaction was not observed in the previous type II crystal. Although most parts of the structure are similar to those in the previous type II structure, the substrate-exit region of the TMD adopts a different configuration in the type I structure. This difference between the two types of structures reflects the flexibility of the substrate-exit region of CmABCB1, which might be essential for the smooth release of various substrates from the transporter

    Real-time chirality transfer monitoring from statistically random to discrete homochiral nanotubes

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    Real time monitoring of chirality transfer processes is necessary to better understand their kinetic properties. Herein, we monitor an ideal chirality transfer process from a statistically random distribution to a diastereomerically pure assembly in real time. The chirality transfer is based on discrete trimeric tubular assemblies of planar chiral pillar[5]arenes, achieving the construction of diastereomerically pure trimers of pillar[5]arenes through synergistic effect of ion pairing between a racemic rim-differentiated pillar[5]arene pentaacid bearing five benzoic acids on one rim and five alkyl chains on the other, and an optically resolved pillar[5]arene decaamine bearing ten amines. When the decaamine is mixed with the pentaacid, the decaamine is sandwiched by two pentaacids through ten ion pairs, initially producing a statistically random mixture of a homochiral trimer and two heterochiral trimers. The heterochiral trimers gradually dissociate and reassemble into the homochiral trimers after unit flipping of the pentaacid, leading to chirality transfer from the decaamine and producing diastereomerically pure trimers

    Effect of Different Types of Upper Instrumented Vertebrae Instruments on Proximal Junctional Kyphosis Following Adult Spinal Deformity Surgery: Pedicle Screw versus Transverse Process Hook

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    Study Design Retrospective comparative study. Purpose To compare the incidence of proximal junctional kyphosis (PJK) between transverse process hooks (TPHs) and pedicle screws (PSs) at the upper instrumented vertebrae (UIV) following adult spinal deformity (ASD) surgery. Overview of Literature The choice of UIV implant type may be important for avoiding PJK; however, few comparative clinical studies have evaluated the incidence of PJK according to the type of UIV implant used in ASD surgery. Methods We retrospectively reviewed 39 consecutive patients with ASD (mean age, 67 years; mean follow-up period, 41 months) who underwent corrective surgery between 2009 and 2013. TPH was used in 17 patients and PS in 22 patients. PJK was defined as the presence of a UIV or UIV±1 fracture, or a change in the proximal junctional angle (PJA) of >20°. Data of patients with TPH and PS were compared. Results The TPH group had a PJK incidence of 17.6% compared with 27.3% in the PS group (p =0.47). In the TPH group, PJK was a result of UIV fracture in one patient, UIV−1 fracture in one patient, and ligamentous failure in one patient. In the PS group, six patients developed PJK because of UIV fracture. No differences in radiographic parameters were found between the two groups. After analyzing the PJA data in the patients with PJK, the changes in PJA were significantly higher in the PS group than in the TPH group (19.0°/5.0°, p =0.04). Conclusions Our results show that using TPH as a UIV implant may not prevent PJK; however, using TPH as the UIV anchor may prevent vertebral collapse if cases of UIV fracture. The increased risk of UIV fracture collapse in the PS group may be a result of a higher mechanical load on UIV when using PS

    High-Tc SQUID magnetometers for use in moderatemagnetically-shielded room

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    We have fabricated and characterized high-Tc planar SQUID magnetometers and first derivative gradiometers with directly-coupled pickup loops. The devices were made from single layer of YBa2Cu3O7-δ thin film on LSAT bicrystal substrate with 30° or 24° misorientation angle. Magnetic properties were investigated by applying a magnetic field B0 for the SQUID magnetometer patterned with holes to reduce the maximum structural width. We found an increasing low frequency noise with cooling fields B0 larger than 1.5 μT. This value consists with the threshold field estimated from the maximum structural width. A magnetic field noise level of 500 fT/Hz1/2 at 10 Hz was observed by using FLL electronics with a bias current reversal in a moderate magnetically-shielded room consisting of only two 1 mm thick layers of permalloy. Measurements of magnetocardiograms demonstrate the suitability of this magnetometer for biomagnetic applications. On the other hand, the gradiometer with two symmetric pickup loops was operated without any shielding. The performance obtained was a field gradient resolution of about 1 pT/cmHz1/2 at 1 kHz and 10 pT/cmHz1/2 at 1 Hz, with a baseline of 4 mm. The imbalance of this gradiometer was around 0.7%, limited by the sensitivity to homogeneous field of the SQUID itself

    Inversion channel diamond metaloxide-semiconductor field-effect transistor with normally off characteristics

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    We fabricated inversion channel diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with normally off characteristics. At present, Si MOSFETs and insulated gate bipolar transistors (IGBTs) with inversion channels are widely used because of their high controllability of electric power and high tolerance. Although a diamond semiconductor is considered to be a material with a strong potential for application in next-generation power devices, diamond MOSFETs with an inversion channel have not yet been reported. We precisely controlled the MOS interface for diamond by wet annealing and fabricated p-channel and planar-type MOSFETs with phosphorus-doped n-type body on diamond (111) substrate. The gate oxide of Al2O3 was deposited onto the n-type diamond body by atomic layer deposition at 300 °C. The drain current was controlled by the negative gate voltage, indicating that an inversion channel with a p-type character was formed at a high-quality n-type diamond body/Al2O3 interface. The maximum drain current density and the field-effect mobility of a diamond MOSFET with a gate electrode length of 5 μm were 1.6 mA/mm and 8.0 cm2/Vs, respectively, at room temperature. © The Author(s) 2016
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