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Light and dark biocidal activity of cationic poly(arylene ethynylene) conjugated polyelectrolytes
Corbitt, Thomas S.,Ding, Liping,Ji, Eunkyung,Ista, Linnea K.,Ogawa, Katsu,Lopez, Gabriel P.,Schanze, Kirk S.,Whitten, David G. Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.7
In this paper we report a study of cationic poly(arylene ethynylene) conjugated polyelectrolytes. The objective of the study was to compare the behavior of a polymer where a thiophene has replaced a phenyl ring in poly(phenylene ethynylene) polycations (PPE) previously investigated. Properties of solution phase and physisorbed suspensions of the polymer on microspheres were investigated. The photophysical properties of the polymer are evaluated and used to understand the striking differences in biocidal activity compared to the PPE polymers previously examined. The principal findings are that the thiophene polymer has remarkable dark biocidal activity against Pseudomonas aeruginosa strain PAO1 but very little light-activated activity. The low light-activated biocidal activity of the thiophene polymer is attributed to a highly aggregated state of the polymer in aqueous solutions and on microspheres as a physisorbed coating. This results in low triplet yields and a very poor sensitization of singlet oxygen and other reactive oxygen intermediates. The highly effective dark biocidal activity of the thiophene-containing polymers is attributed to its high lipophilicity and the presence of accessible quaternary ammonium groups. The difference in behavior among the polymers compared provides insights into the mechanism of the dark process and indicates that aggregation of polymer can reduce light activated biocidal activity by suppressing singlet oxygen generation.
Watanabe, H.,Lorusso, G.,Nishimura, S.,Otsuka, T.,Ogawa, K.,Xu, Z. Y.,Sumikama, T.,Sö,derströ,m, P.-A.,Doornenbal, P.,Li, Z.,Browne, F.,Gey, G.,Jung, H. S.,Taprogge, J.,Vajta, Zs.,Wu, J.,Yagi, American Physical Society 2014 Physical Review Letters Vol.113 No.4
<P>A new isomer with a half-life of 23.0(8) ms has been identified at 2406 keV in (126)Pd and is proposed to have a spin and parity of 10(+) with a maximally aligned configuration comprising two neutron holes in the 1h(11/2) orbit. In addition to an internal-decay branch through a hindered electric octupole transition, β decay from the long-lived isomer was observed to populate excited states at high spins in (126)Ag. The smaller energy difference between the 10(+) and 7(-) isomers in (126)Pd than in the heavier N=80 isotones can be interpreted as being ascribed to the monopole shift of the 1h(11/2) neutron orbit. The effects of the monopole interaction on the evolution of single-neutron energies below (132)Sn are discussed in terms of the central and tensor forces.</P>
Kim, T,Yoshida, K,Kim, Y K,Tyndel, M S,Park, H J,Choi, S H,Ahn, J-S,Jung, S-H,Yang, D-H,Lee, J-J,Kim, H J,Kong, G,Ogawa, S,Zhang, Z,Kim, H J,Kim, D D Macmillan Publishers Limited 2016 Leukemia Vol.30 No.2
<P>Most types of cancers are made up of heterogeneous mixtures of genetically distinct subclones. In particular, acute myeloid leukemia (AML) has been shown to undergo substantial clonal evolution over the course of the disease. AML tends to harbor fewer mutations than solid tumors, making it challenging to infer clonal structure. Here, we present a 9-year, whole-exome sequencing study of a single case at 12 time points, from the initial diagnosis until a fourth relapse, including 6 remission samples in between. To the best of our knowledge, it covers the longest time span of any data set of its kind. We used these time series data to track the hierarchy and order of variant acquisition, and subsequently analyzed the evolution of somatic variants to infer clonal structure. From this, we postulate the development and extinction of subclones, as well as their anticorrelated expansion via varying drug responses. In particular, we show that new subclones started appearing after the first complete remission. The presence and absence of different subclones during remission and relapses implies differing drug responses among subclones. Our study shows that time series analysis contrasting remission and relapse periods provides a much more comprehensive view of clonal structure and evolution.</P>
Abe, K.,Hiraide, K.,Ichimura, K.,Kishimoto, Y.,Kobayashi, K.,Kobayashi, M.,Moriyama, S.,Nakahata, M.,Norita, T.,Ogawa, H.,Sato, K.,Sekiya, H.,Takachio, O.,Takeda, A.,Tasaka, S.,Yamashita, M.,Yang, B.S Elsevier 2018 Nuclear Instruments & Methods in Physics Research. Vol.884 No.-
<P><B>Abstract</B></P> <P>We established a method to assay <SUP>210</SUP>Pb and <SUP>210</SUP>Po contaminations in the bulk of copper samples using a low-background alpha particle counter. The achieved sensitivity for the <SUP>210</SUP>Pb and <SUP>210</SUP>Po contaminations reaches a few mBq/kg. Due to this high sensitivity, the <SUP>210</SUP>Pb and <SUP>210</SUP>Po contaminations in oxygen free copper bulk were identified and measured for the first time. The <SUP>210</SUP>Pb contaminations of our oxygen free copper samples were 17–40 mBq/kg. Based on our investigation of copper samples in each production step, the <SUP>210</SUP>Pb in oxygen free copper was understood to be a small residual of an electrolysis process. This method to measure bulk contaminations of <SUP>210</SUP>Pb and <SUP>210</SUP>Po could be applied to other materials.</P>
Search for sub-GeV dark matter by annual modulation using XMASS-I detector
Kobayashi, M.,Abe, K.,Hiraide, K.,Ichimura, K.,Kishimoto, Y.,Kobayashi, K.,Moriyama, S.,Nakahata, M.,Ogawa, H.,Sato, K.,Sekiya, H.,Suzuki, T.,Takeda, A.,Tasaka, S.,Yamashita, M.,Yang, B.S.,Kim, N.Y.,K North-Holland Pub. Co 2019 Physics letters. Section B Vol.795 No.-
<P><B>Abstract</B></P> <P>A search for dark matter (DM) with mass in the sub-GeV region (0.32–1 GeV) was conducted by looking for an annual modulation signal in XMASS, a single-phase liquid xenon detector. Inelastic nuclear scattering accompanied by bremsstrahlung emission was used to search down to an electron equivalent energy of 1 keV. The data used had a live time of 2.8 years (3.5 years in calendar time), resulting in a total exposure of 2.38 ton-years. No significant modulation signal was observed and 90% confidence level upper limits of 1.6 × <SUP> 10 − 33 </SUP> cm<SUP>2</SUP> at 0.5 GeV was set for the DM-nucleon cross section. This is the first experimental result of a search for DM mediated by the bremsstrahlung effect. In addition, a search for DM with mass in the multi-GeV region (4–20 GeV) was conducted with a lower energy threshold than previous analysis of XMASS. Elastic nuclear scattering was used to search down to a nuclear recoil equivalent energy of 2.3 keV, and upper limits of 2.9 × <SUP> 10 − 42 </SUP> cm<SUP>2</SUP> at 8 GeV was obtained.</P>
Search for dark matter in the form of hidden photons and axion-like particles in the XMASS detector
Abe, K.,Hiraide, K.,Ichimura, K.,Kishimoto, Y.,Kobayashi, K.,Kobayashi, M.,Moriyama, S.,Nakahata, M.,Ogawa, H.,Sato, K.,Sekiya, H.,Suzuki, T.,Takachio, O.,Takeda, A.,Tasaka, S.,Yamashita, M.,Yang, B.S Elsevier 2018 Physics letters: B Vol.787 No.-
<P><B>Abstract</B></P> <P>Hidden photons and axion-like particles are candidates for cold dark matter if they were produced non-thermally in the early universe. We conducted a search for both of these bosons using 800 live-days of data from the XMASS detector with 327 kg of liquid xenon in the fiducial volume. No significant signal was observed, and thus we set constraints on the <SUP> α ′ </SUP> / α parameter related to kinetic mixing of hidden photons and the coupling constant <SUB> g A e </SUB> of axion-like particles in the mass range from 40 to 120 keV/ <SUP> c 2 </SUP> , resulting in <SUP> α ′ </SUP> / α < 6 × <SUP> 10 − 26 </SUP> and <SUB> g A e </SUB> < 4 × <SUP> 10 − 13 </SUP> . These limits are the most stringent over this mass range derived from both direct and indirect searches to date.</P>
First study of neutron tagging with a water Cherenkov detector
The Super-Kamiokande Collaboration,Watanabe, H.,Zhang, H.,Abe, K.,Hayato, Y.,Iida, T.,Ikeda, M.,Kameda, J.,Kobayashi, K.,Koshio, Y.,Miura, M.,Moriyama, S.,Nakahata, M.,Nakayama, S.,Obayashi, Y.,Ogawa, North-Holland 2009 Astroparticle physics Vol.31 No.4
A first study of neutron tagging is conducted in Super-Kamiokande, a 50,000 ton water Cherenkov detector. The tagging efficiencies of thermal neutrons are evaluated in a 0.2% GdCl<SUB>3</SUB>-water solution and pure water. They are determined to be, respectively, 66.7% for events above 3MeV and 20% with corresponding background probabilities of 2x10<SUP>-4</SUP> and 3x10<SUP>-2</SUP>. This newly developed technique may enable water Cherenkov detectors to identify ν@?<SUB>e</SUB>'s from astrophysical sources as well as those produced by commercial reactors via the delayed coincidence scheme.
Numerical Simulation of Deagration-to-Detonation Transition in Obstructed Spaces
Takanobu Ogawa,Vadim N. Gamezo,Elaine S. Oran 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.11
We numerically simulate deflagration-to-detonation transition(DDT) in obstructed spaces. The twodimensional, chemically reactive, compressible Navier-Stokes equations are solved with an explicit second-order finite volume method. The reaction model is based on one-step Arrhenius kinetics and is calibrated to reproduce the correct speeds for a flame and a detonation. An adaptive Cartesian mesh is used to enhance the resolution of reaction fronts and shocks, and is organized with the Fully Threaded Tree data structure. The numerical results show the series of events leading to flame acceleration, shock formation, shock-flame interactions, DDT, and detonation propagation. Obstacles have significant effect on each process through their interactions with flows and shocks. The flow passing over an obstacle causes flow instabilities, which accelerate the flame through flame wrinkling. Frequent shock reflection from obstacles promotes shock-flame interactions and DDT. As a result, the layout of obstacles alters how and where DDT occurs.