Multielement Analysis of Biological and Geological Materials by Charged Particle Activation

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High Permeability and Low Core Losses of Nanocrystalline Fe-Nb-Zr-B-Cu Alloys

Nanocrystalline Fe-M-B (M=Zr or Nb) alloys prepared by crystallization of rapidly quenched amorphous ribbons are known as a new class of soft magnets with high saturation magnetization. In order to improve their soft magnetic properties further, the reduction of their magnetostriction to zero was attempted by a combined addition of Zr and Nb, because the signs of the magnetostriction of the Fe-Zr-B and the Fe-Nb-B at each optimum condition are known to be opposite. Further, the B concentration was reinvestigated under a Cu addition and the combined addition of Zr and Nb in order to further refine the grain size and to improve the intergranular exchange coupling. As a result, the small average grain size of 8nm and nearly zero magnetostriction has been simultaneously obtained in the Fe_Nb_Zr_B_8Cu_1 alloy. This alloy simultaneously exhibits the high permeability of 100, 000 (at 1kHz) and the high saturation flux density of 1.53T, satisfying the both properties in the highest level among the rapidly quenched ribbons ever reported. The core losses of the nanocrystalline Fe_Nb_Zr_B_8Cu_1 alloy are lower than those of the amorphous Fe-Si-B alloys over a wide frequency and Bm (maximum induction) range. Further, the core losses are almost unchanged under the stresses such as epoxy resin molding. These new nanocrystalline materials are suitable for use in advanced electronic devices such as inductors or transformers

Modulation of Amide Bond Rotamers in 5-Acyl-6,7-dihydrothieno[3,2-c]pyridines

2-Substituted <i>N</i>-acyl-piperidine is a widespread and important structural motif, found in approximately 500 currently available structures, and present in nearly 30 pharmaceutically active compounds. Restricted rotation of the acyl substituent in such molecules can give rise to two distinct chemical environments. Here we demonstrate, using NMR studies and density functional theory modeling of the lowest energy structures of 5-acyl-6,7-dihydrothieno­[3,2-<i>c</i>]­pyridine derivatives, that the amide <i>E</i>:<i>Z</i> equilibrium is affected by non-covalent interactions between the amide oxygen and adjacent aromatic protons. Structural predictions were used to design molecules that promote either the <i>E</i>- or <i>Z</i>-amide conformation, enabling preparation of compounds with a tailored conformational ratio, as proven by NMR studies. Analysis of the available X-ray data of a variety of published <i>N</i>-acyl-piperidine-containing compounds further indicates that these molecules are also clustered in the two observed conformations. This finding emphasizes that directed conformational isomerism has significant implications for the design of both small molecules and larger amide-containing molecular architectures

Rapid generation of long synthetic tandem repeats and its application for analysis in human artificial chromosome formation

Human artificial chromosomes (HACs) provide a unique opportunity to study kinetochore formation and to develop a new generation of vectors with potential in gene therapy. An investigation into the structural and the functional relationship in centromeric tandem repeats in HACs requires the ability to manipulate repeat substructure efficiently. We describe here a new method to rapidly amplify human alphoid tandem repeats of a few hundred base pairs into long DNA arrays up to 120 kb. The method includes rolling-circle amplification (RCA) of repeats in vitro and assembly of the RCA products by in vivo recombination in yeast. The synthetic arrays are competent in HAC formation when transformed into human cells. As short multimers can be easily modified before amplification, this new technique can identify repeat monomer regions critical for kinetochore seeding. The method may have more general application in elucidating the role of other tandem repeats in chromosome organization and dynamics

Saturation Magnetostriction and Volume Magnetostriction of Amorphous Ribbons Based on Fe-Ni and Fe-Co

The saturation magnetostriction and the forced volume magnetostriction of Fe-Ni and Fe-Co amorphous ribbons were measured from 77°K to room temperature by a three terminal capacitance method. It was found that the magnetostriction was nearly isotropic. In Fe-Ni amorphous system, the saturation λ_s and the volume magnetostriction constants δω/δH decreased monotonously with the increase of Ni concentration from 31×10^ and 21×10^/Oe respectively for Fe_P_C_ to 15×10^ and 7×10^/Oe respectively for Fe_Ni_P_C_. The temperature dependence of the saturation magnetostriction was not simple decreasing function of the temperature. In Fe-Co system, there was a remarkable change of the sign of the magnetostriction nearly equal to Fe_Co_Si_B_

Characterization of hedgehog acyltransferase inhibitors identifies a small molecule probe for hedgehog signaling by cancer cells

The Sonic Hedgehog (Shh) signaling pathway plays a critical role during embryonic development and cancer progression. N-terminal palmitoylation of Shh by Hedgehog acyltransferase (Hhat) is essential for efficient signaling, raising interest in Hhat as a novel drug target. A recently identified series of dihydrothienopyridines has been proposed to function via this mode of action; however, the lead compound in this series (RUSKI-43) was subsequently shown to possess cytotoxic activity unrelated to canonical Shh signaling. To identify a selective chemical probe for cellular studies, we profiled three RUSKI compounds in orthogonal cell-based assays. We found that RUSKI-43 exhibits off-target cytotoxicity, masking its effect on Hhat-dependent signaling, hence results obtained with this compound in cells should be treated with caution. In contrast, RUSKI-201 showed no off-target cytotoxicity, and quantitative whole-proteome palmitoylation profiling with a bioorthogonal alkyne-palmitate reporter demonstrated specific inhibition of Hhat in cells. RUSKI-201 is the first selective Hhat chemical probe in cells and should be used in future studies of Hhat catalytic function

A new approach towards volumetric assessment of left ventricular function with MSCT

Cardiovascular CT is considered the diagnostic standard for establishing the presence of a functional and dynamic imaging system. It is difficult, however, to estimate the ventricular motion and volumes that are processed using hundreds and thousands of CT images, in a few moments

Zero Magnetostriction and Extremely Low Residual Magnetic Loss in Fe-Co Amorphous Ribbons

application/pdfThe initial permeability μ_i, the loss factor tan δ, and the inverse quality factor tan δ/μ_i of Fe_5Co_Si_B_ ribbons 35 μm, 30 μm, 25 μm and 21 μm in thickness were measured with a Maxwell Bridge from room temperature to 140℃ in the high-frequency region from 3 kHz to 500 kHz. The initial permeability of the ribbon 21 μm in thickness was about 10, 600 at 3 kHz and 4300 at 500 kHz. The residual loss coefficient C_1 and the hysteresis loss coefficient h_1 were extremely low, about 8×10^ and 60 (cm/A), respectively. In the high-frequency region, the eddy current loss term increases with the square of the thickness of the ribbons and plays the most important part of all the magnetic losses.紀要類(bulletin)70514 bytesdepartmental bulletin pape

Observation of the Magnetostriction in Ferromagnetic Amorphous Thin Ribbons

The first observation of the magnetostriction of the amorphous thin ribbons was made at room temperature, and it was found that in Fe_P_C_, the saturation magnetostriction λ in the plane was 18.5×10^ which was several times bigger than that of bulk iron in the polycrystalline state