465 research outputs found
A remark on non-commutative -spaces
We describe the Haagerup and the Kosaki non-commutative -spaces
associated with a tensor product von Neumann algebra in
terms of those associated with . The descriptions are then shown to be
useful in the quantum information theory based on operator algebras.Comment: Comments welcom
Collisional stability of localized Yb() atoms immersed in a Fermi sea of Li
We establish an experimental method for a detailed investigation of inelastic
collisional properties between ytterbium (Yb) in the metastable
state and ground state lithium (Li). By combining an optical
lattice and a direct excitation to the state we achieve high
selectivity on the collisional partners. Using this method we determine
inelastic loss coefficients in collisions between
Yb() with magnetic sublevels of and and
ground state Li to be
and , respectively. Absence
of spin changing processes in Yb()-Li inelastic collisions at
low magnetic fields is confirmed by inelastic loss measurements on the
state. We also demonstrate that our method allows us to look into loss
processes in few-body systems separately.Comment: 12 pages, 7 figure
Synthesis of Pyrrolo [2,1-b] thiazolines Using N-(Trimethylsilylmethyl)-2- methylthiothiazolinium Trifluoromethanesulfonate
N-(Trimethylsilylmethyl)-2-methylthiothiazolinium trifluoromethanesulfonate(4), readily prepard from 2-methylthiothiazoline (2) and trimethylsilylmethyl trifluoromethenesulfonate (1), reacted with activated alkenes (5) and alkynes (6) in the presence of cesium fluoride in acetonitrile to give the corresponding 4, 5-dihydropyrrolo [2, 1-b] thiazoline and pyrrolo [2, 1-b] thiazoline derivatives. The 1, 3-dipolar cycloaddition reaction is one of the most important reaction to construct five-membered heterocycles. We have reported that tailor-made azomethine and thiocarbonyl ylids can be generated by the 1, 3-elimionation reaction of trimethylsilylmethyl- substituted ketene N,S- or S,S- acetals promoted by fluoride ion and react with dipolarophiles to give five-membered heterocycles. As an unpublished result, we have recognized that the reactuion of 3-trimethylsilylmethylamino-3-methylthio-2- cyanoacrylonitrile with dipolarophiles in the presence of a fluoride ion gives five-membered heterocycles but the reaction of 3-trimethylsilylmethylamino-2-cyanoacrylonitrile with dipolarophiles gives no cycloadducts. These facts have shown that the elimination of a methylthio group following cleavage of carbon-silicon bond is a useful tool for the generation of 1,3-dipolar. Here we descrive the reaction of N-(trimethylsilylmethyl)-2- methythiothiazolinium trifluoromethanesulfonate, which has a Me3SiCH2 -N=C-SMe system, with dipolarophiles gives 4,5-dihydropyrrolo [2,1 - b] thiazoline derivatives. Trimethysilylmethyl trifluoromethanesulfonate (1) is an interesting compound to the preparation of silicon-containing sulfonium, nitrogen and other ylids. Starting material 1 was prepared according to the literature. A solution of 2-methylthiothiazoline (2) in dichloromethane was treated with 1 and stirred at room temperature for over night. After the solvent was removed N- (trimethylsilymethyl)-2-methylthiothiazolinium trifluoromethanesulfonate (4) was afforded. The crude salt 4 was used in the next step without purification. A solution of 4, thus obtained, and dimethyl fumarate(6b) in the prsence of cesium fluoride in acetonitrile was stirred at room temperature for 24h. The usual work-up after treatment with aqueous ammonium chloride and separation by preparative t.l.c. gave dimethyl 4,5-dihydropyrrolo [2, 1-b] thiazoline -5, 6-dicarboxylate(7b), formal [3+2] cycloaddition product, in 53% yield. The cycloadditon behavior of an unsymmetrically substituted dipolarophile was studied to determine the regioselectivity of the reaction. The reaction of 4 and methyl acrylate (6a) under the similar conditions gave methyl 4,5-dihydop yrrolo [2,1-b] thiazoline-6-carboxylate (7a) in 57% yield, exclusively. When methyl cinnamate (6d) was used as a dipolarophile, cycloadduct 7d was obtained as a single pro duct. The representative results are listed in Table 1. N-(Trimethylsilylmethyl)-2- methylthiobenzothia-zolium trifluoromethenesulfonate (5) was also prepared and reacted with activated alkenes (6a-6d) to give the corresponding [3+2] cycloadducts (8a-8d) in a manner similar to that described for 7a. The reaction also shows complete regiospecificity in the cycloaddition with unsymmetrically substituted olefins. However the reactions of 4 and 5 with N-methylmaleimide was unsuccessful under the present reaction conditions. Salt 4 and 5 reacted with alkynes (9a and 9b) under the similar conditions to give [3+2] cycloaiddition products, pyrrolo [2, 1-b] thiazoline derivatives(10a and 10b) and pyrrolo [2, 1-b] benzothiazole derivatives (11a and 11b). (see Table 2) This work demonstrates a mild and simple procedure for the preparation of pyrrolo [2, 1-b] thiazoline and pyrrolo [2, 1-b] benzothiazole derivatives
Fabrication of submicron LaSrCuO intrinsic Josephson junction stacks
Intrinsic Josephson junction (IJJ) stacks of cuprate superconductors have
potential to be implemented as intrinsic phase qubits working at relatively
high temperatures. We report success in fabricating submicron
LaSrCuO (LSCO) IJJ stacks carved out of single crystals. We
also show a new fabrication method in which argon ion etching is performed
after focused ion beam etching. As a result, we obtained an LSCO IJJ stack in
which resistive multi-branches appeared. It may be possible to control the
number of stacked IJJs with an accuracy of a single IJJ by developing this
method.Comment: 5 pages, 6 figure
Cold Molecular Gas Along the Merger Sequence in Local Luminous Infrared Galaxies
We present an initial result from the 12CO (J=1-0) survey of 79 galaxies in
62 local luminous and ultra-luminous infrared galaxy (LIRG and ULIRG) systems
obtained using the 45 m telescope at the Nobeyama Radio Observatory. This is
the systematic 12CO (J=1-0) survey of the Great Observatories All-sky LIRGs
Survey (GOALS) sample. The molecular gas mass of the sample ranges 2.2 x 10^8 -
7.0 x 10^9 Msun within the central several kiloparsecs subtending 15" beam. A
method to estimate a size of a CO gas distribution is introduced, which is
combined with the total CO flux in the literature. The method is applied to a
part of our sample and we find that the median CO radius is 1-4 kpc. From the
early stage to the late stage of mergers, we find that the CO size decreases
while the median value of the molecular gas mass in the central several kpc
region is constant. Our results statistically support a scenario where
molecular gas inflows towards the central region from the outer disk, to
replenish gas consumed by starburst, and that such a process is common in
merging LIRGs.Comment: 25 pages, 22 figures, accepted for publication in Ap
Comparative Secretome and Functional Analyses Reveal Glycoside Hydrolase Family 30 and Cysteine Peptidase as Virulence Determinants in the Pinewood Nematode Bursaphelenchus xylophilus
Pine wilt disease, caused by the pinewood nematode, Bursaphelenchus xylophilus, is one of the world’s most serious tree diseases. Although the B. xylophilus whole-genome sequence and comprehensive secretome profile have been determined over the past decade, it remains unclear what molecules are critical in pine wilt disease and govern B. xylophilus virulence in host pine trees. Here, a comparative secretome analysis among four isolates of B. xylophilus with distinct virulence levels was performed to identify virulence determinants. The four candidate virulence determinants of B. xylophilus highly secreted in virulent isolates included lipase (Bx-lip1), glycoside hydrolase family 30 (Bx-GH30), and two C1A family cysteine peptidases (Bx-CAT1 and Bx-CAT2). To validate the quantitative differences in the four potential virulence determinants among virulence groups at the protein level, we used real-time reverse-transcription polymerase chain reaction analysis to investigate these determinants at the transcript level at three time points: pre-inoculation, 3 days after inoculation (dai), and 7 dai into pine seedlings. The transcript levels of Bx-CAT1, Bx-CAT2, and Bx-GH30 were significantly higher in virulent isolates than in avirulent isolates at pre-inoculation and 3 dai. A subsequent leaf-disk assay based on transient overexpression in Nicotiana benthamiana revealed that the GH30 candidate virulent factor caused cell death in the plant. Furthermore, we demonstrated that Bx-CAT2 was involved in nutrient uptake for fungal feeding via soaking-mediated RNA interference. These findings indicate that the secreted proteins Bx-GH30 and Bx-CAT2 contribute to B. xylophilus virulence in host pine trees and may be involved in pine wilt disease
Genetic Characterization of Hepatitis C Virus in Long-Term RNA Replication Using Li23 Cell Culture Systems
Background
The most distinguishing genetic feature of hepatitis C virus (HCV) is its remarkable diversity and variation. To understand this feature, we previously performed genetic analysis of HCV in the long-term culture of human hepatoma HuH-7-derived HCV RNA-replicating cell lines. On the other hand, we newly established HCV RNA-replicating cell lines using human hepatoma Li23 cells, which were distinct from HuH-7 cells.
Methodology/Principal Findings
Li23-derived HCV RNA-replicating cells were cultured for 4 years. We performed genetic analysis of HCVs recovered from these cells at 0, 2, and 4 years in culture. Most analysis was performed in two separate parts: one part covered from the 5′-terminus to NS2, which is mostly nonessential for RNA replication, and the other part covered from NS3 to NS5B, which is essential for RNA replication. Genetic mutations in both regions accumulated in a time-dependent manner, and the mutation rates in the 5′-terminus-NS2 and NS3-NS5B regions were 4.0–9.0×10−3 and 2.7–4.0×10−3 base substitutions/site/year, respectively. These results suggest that the variation in the NS3-NS5B regions is affected by the pressure of RNA replication. Several in-frame deletions (3–105 nucleotides) were detected in the structural regions of HCV RNAs obtained from 2-year or 4-year cultured cells. Phylogenetic tree analyses clearly showed that the genetic diversity of HCV was expanded in a time-dependent manner. The GC content of HCV RNA was significantly increased in a time-dependent manner, as previously observed in HuH-7-derived cell systems. This phenomenon was partially due to the alterations in codon usages for codon optimization in human cells. Furthermore, we demonstrated that these long-term cultured cells were useful as a source for the selection of HCV clones showing resistance to anti-HCV agents.
Conclusions/Significance
Long-term cultured HCV RNA-replicating cells are useful for the analysis of evolutionary dynamics and variations of HCV and for drug-resistance analysis
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