355 research outputs found

    Modification of a neuronal network direction using stepwise photo-thermal etching of an agarose architecture

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    Control over spatial distribution of individual neurons and the pattern of neural network provides an important tool for studying information processing pathways during neural network formation. Moreover, the knowledge of the direction of synaptic connections between cells in each neural network can provide detailed information on the relationship between the forward and feedback signaling. We have developed a method for topographical control of the direction of synaptic connections within a living neuronal network using a new type of individual-cell-based on-chip cell-cultivation system with an agarose microchamber array (AMCA). The advantages of this system include the possibility to control positions and number of cultured cells as well as flexible control of the direction of elongation of axons through stepwise melting of narrow grooves. Such micrometer-order microchannels are obtained by photo-thermal etching of agarose where a portion of the gel is melted with a 1064-nm infrared laser beam. Using this system, we created neural network from individual Rat hippocampal cells. We were able to control elongation of individual axons during cultivation (from cells contained within the AMCA) by non-destructive stepwise photo-thermal etching. We have demonstrated the potential of our on-chip AMCA cell cultivation system for the controlled development of individual cell-based neural networks

    Sequential C−F Bond Transformation of the Difluoromethylene Unit in Perfluoroalkyl Groups: A Combination of Fine-Tuned Phenothiazine Photoredox Catalyst and Lewis Acid

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    Sugihara N., Nishimoto Y., Osakada Y., et al. Sequential C−F Bond Transformation of the Difluoromethylene Unit in Perfluoroalkyl Groups: A Combination of Fine-Tuned Phenothiazine Photoredox Catalyst and Lewis Acid. Angewandte Chemie - International Edition 63, e202401117 (2024); https://doi.org/10.1002/anie.202401117.A sequential process via photoredox catalysis and Lewis acid mediation for C−F bond transformation of the CF2 unit in perfluoroalkyl groups has been achieved to transform perfluoroalkylarenes into complex fluoroalkylated compounds. A phenothiazine-based photocatalyst promotes the defluoroaminoxylation of perfluoroalkylarenes with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) under visible light irradiation, affording the corresponding aminoxylated products. These products undergo a further defluorinative transformation with various organosilicon reagents mediated by AlCl3 to provide highly functionalized perfluoroalkyl alcohols. Our novel phenothiazine catalyst works efficiently in the defluoroaminoxylation. Transient absorption spectroscopy revealed that the catalyst regeneration step is crucial for the photocatalytic aminoxylation

    Low energy indium or gallium ion implantations to SiO2 thin films for development of novel catalysts

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    It has been demonstrated that indium (In) implanted silicon dioxide (SiO thin films catalyze a reaction of benzhydrol with acetylacetone. In this study, it is found that the threshold In ion incident energy for manifestation of the catalytic effect exists between 400 and 470 eV. Furthermore, a technique to implant gallium (Ga) to SiOfilms has been developed with highly controlled doses and injection energies for the formation of thin films that promote Ga catalysts. The efficiency of catalytic reactions by Ga implanted SiOthin films is yet to be improved. Unlike In implanted SiO2, the reason why no significant reaction was observed in the case of Ga implanted SiOfilms examined in this study seems that the Ga ion energy was so low that deposited surface Ga atoms should lack interactions with Si atoms for the manifestation of catalytic reaction. © 2014 The Surface Science Society of Japan.Satoru Yoshimura, Masato Kiuchi, Yoshihiro Nishimoto, Makoto Yasuda, Akio Baba, Satoshi Hamaguchi, Low Energy Indium or Gallium Ion Implantations to SiO2 Thin Films for Development of Novel Catalysts, e-Journal of Surface Science and Nanotechnology, 2014, Volume 12, Pages 197-202, Released April 26, 2014, Online ISSN 1348-0391, https://doi.org/10.1380/ejssnt.2014.197, https://www.jstage.jst.go.jp/article/ejssnt/12/0/12_197/_article/-char/e

    Long-term monitoring of the short period SU UMa-type dwarf nova, V844 Herculis

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    We report on time-resolved CCD photometry of four outbursts of a short-period SU UMa-type dwarf nova, V844 Herculis. We successfully determined the mean superhump periods to be 0.05584(64) days, and 0.055883(3) for the 2002 May superoutburst, and the 2006 April-May superoutburst, respectively. During the 2002 October observations, we confirmed that the outburst is a normal outburst, which is the first recorded normal outburst in V844 Her. We also examined superhump period changes during 2002 May and 2006 April-May superoutbursts, both of which showed increasing superhump period over the course of the plateau stage. In order to examine the long-term behavior of V844 Her, we analyzed archival data over the past ten years since the discovery of this binary. Although photometry is not satisfactory in some superoutbursts, we found that V844 Her showed no precursors and rebrightenings. Based on the long-term light curve, we further confirmed V844 Her has shown almost no normal outbursts despite the fact that the supercycle of the system is estimated to be about 300 days. In order to explain the long-term light curves of V844 Her, evaporation in the accretion disk may play a role in the avoidance of several normal outbursts, which does not contradict with the relatively large X-ray luminosity of V844 Her.Comment: 10 pages, 11 figures, accepted for PAS

    X-ray diffractometry for the structure determination of a submicrometre single powder grain

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    A high-precision diffractometer with a synchrotron radiation microfocusing technique has been developed to investigate the crystal structure of a submicrometre-scale single grain of powder sample. The structure of a BaTiO3 single powder grain, of dimensions ∼600 × 600 × 300 nm, was determined

    Long-Term Outcome after Bone Marrow Transplantation for Aplastic Anemia Using Cyclophosphamide and Total Lymphoid Irradiation as Conditioning Regimen

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    AbstractWe retrospectively studied 49 patients in a single institute to evaluate the long-term outcome of total lymphoid irradiation (TLI) conditioning for allogeneic stem cell transplantation (allo-SCT) to treat aplastic anemia (AA). Most of the patients had received transfusions and had undergone previous treatment, with 33 receiving related transplants and 16 receiving unrelated transplants. Conditioning consisted of cyclophosphamide (Cy; 200 mg/kg) plus TLI (750 cGy) for related transplantation and Cy plus total body irradiation (TBI; 500 cGy) and TLI (500 cGy) for unrelated transplantation. Antithymocyte globulin (ATG) was added for 6 of the unrelated transplantations. Graft-versus-host-disease (GVHD) prophylaxis consisted mainly of cyclosporine (CSA) and methotrexate (MTX). Graft failure developed in 2 patients (4.1%). With a median follow-up of 7 years, overall survival (OS) was 81% and was not statistically significantly different between the patients receiving related transplants and those receiving unrelated transplants. In multivariate analyses, a history of previous treatment with ATG was the sole factor associated with a worse survival rate, and the interval from diagnosis to treatment was not prognostic. The incidence of acute (grade II to IV) GVHD (aGVHD) was 23%, and that of chronic GVHD (cGVHD) was 29%. Female-to-male transplantation was the sole factor associated with chronic GVHD. B cell lymphoproliferative disorder developed only after the ATG-containing conditioning. No other secondary malignancies developed after long-term follow-up. Our findings suggest that TLI conditioning is feasible and effective for patients with AA
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