284 research outputs found
Effect of anthocyanin composition in grape skin on anthocyanic vacuolar inclusion development and skin coloration
Berry skin coloration, the content and composition of anthocyanin and anthocyanic vacuolar inclusion (AVI) development were investigated in two black cultivars, Cabernet Sauvignon (Vitis vinifera) and Pione (V. vinifera Ć V. labrusca, 4x), and one red cv., Red Port (V. vinifera Ć V. labrusca). Pione had lower L* (lightness of the skin) and higher color index values than Cabernet Sauvignon, indicating that Pione had darker skin color than Cabernet Sauvignon. The two black cultivars had high contents of malvidin, while the major anthocyanidin of Red Port was cyanidin and delphinidin. This difference of anthocyanidin composition was responsible for the red color of Red Port. Whereas the anthocyanidin composition of the two black cultivars showed little difference, the percentage of acylated anthocyanins was markedly higher in Pione than in Cabernet Sauvignon. The diameter of AVIs was similar between Pione and Cabernet Sauvignon, but the density of AVIs was higher in cv. Pione. This difference in AVI development affects grape skin coloration. A comparison of the anthocyanin composition in isolated AVIs and that in whole cell tissue showed that in all three cultivars the percentage of acylated anthocyanins was high in the AVIs. In Pione skins the high percentage of acylated anthocyanins might result in many AVIs to be formed, and might be responsible for the dark coloration.
Angle-resolved photoemission study of MX-chain compound [Ni(chxn)Br]Br
We report on the results of angle-resolved photoemission experiments on a
quasi-one-dimensional -chain compound [Ni(chxn)Br]Br (chxn =
1,2-cyclohexanediamine), a one-dimensional Heisenberg system with
and K, which shows a gigantic non-linear optical effect. A "band"
having about 500 meV energy dispersion is found in the first half of the
Brillouin zone , but disappears at . Two
dispersive features, expected from the spin-charge separation, as have been
observed in other quasi-one-dimensional systems like SrCuO, are not
detected. These characteristic features are well reproduced by the -
chain model calculations with a small charge-transfer energy compared
with that of one-dimensional Cu-O based compounds. We propose that this smaller
is the origin of the absence of clear spin- and charge-separation in
the photoemission spectra and strong non-linear optical effect in
[Ni(chxn)Br]Br.Comment: 4 pages, 3 figure
Discovery of possible molecular counterparts to the infrared Double Helix Nebula in the Galactic center
We have discovered two molecular features at radial velocities of -35 km/s
and 0 km/s toward the infrared Double Helix Nebula (DHN) in the Galactic center
with NANTEN2. The two features show good spatial correspondence with the DHN.
We have also found two elongated molecular ridges at these two velocities
distributed vertically to the Galactic plane over 0.8 degree. The two ridges
are linked by broad features in velocity and are likely connected physically
with each other. The ratio between the 12CO J=2-1 and J=1-0 transitions is 0.8
in the ridges which is larger than the average value 0.5 in the foreground gas,
suggesting the two ridges are in the Galactic center. An examination of the K
band extinction reveals a good coincidence with the CO 0 km/s ridge and is
consistent with a distance of 8 +/-2 kpc. We discuss the possibility that the
DHN was created by a magnetic phenomenon incorporating torsional Alfv\'en waves
launched from the circumnuclear disk (Morris, Uchida & Do 2006) and present a
first estimate of the mass and energy involved in the DHN.Comment: 32 pages, 23 figures, Accepted by Ap
Genomic characterization of antibiotic resistanceāencoding genes in clinical isolates of Vibrio cholerae nonāO1/nonāO139 strains from Kolkata, India: generation of novel types of genomic islands containing plural antibiotic resistance genes
NonāO1/nonāO139 nontoxigenic Vibrio cholerae associated with choleraālike diarrhea has been reported in Kolkata, India. However, the property involved in the pathogenicity of these strains has remained unclear. The character of 25 nonāO1/nonāO139 nontoxigenic V. cholerae isolated during 8 years from 2007 to 2014 in Kolkata was examined. Determination of the serogroup showed that the serogroups O6, O10, O35, O36, O39, and O70 were represented by two strains in each serogroup, and the remaining isolates belonged to different serogroups. To clarify the character of antibiotic resistance of these isolates, an antibiotic resistance test and the gene analysis were performed. According to antimicrobial drug susceptibility testing, 13 strains were classified as drug resistant. Among them, 10 strains were quinolone resistant and 6 of the 13 strains were resistant to more than three antibiotics. To define the genetic background of the antibiotic character of these strains, wholeāgenome sequences of these strains were determined. From the analysis of these sequences, it becomes clear that all quinolone resistance isolates have mutations in quinolone resistanceādetermining regions. Further research on the genome sequence showed that four strains possess Class 1 integrons in their genomes, and that three of the four integrons are found to be located in their genomic islands. These genomic islands are novel types. This indicates that various integrons containing drug resistance genes are spreading among V. cholerae nonāO1/nonāO139 strains through the action of newly generated genomic islands
Charge-Transfer Excitations in One-Dimensional Dimerized Mott Insulators
We investigate the optical properties of one-dimensional (1D) dimerized Mott
insulators using the 1D dimerized extended Hubbard model. Numerical
calculations and a perturbative analysis from the decoupled-dimer limit clarify
that there are three relevant classes of charge-transfer (CT) states generated
by photoexcitation: interdimer CT unbound states, interdimer CT exciton states,
and intradimer CT exciton states. This classification is applied to
understanding the optical properties of an organic molecular material,
1,3,5-trithia-2,4,6-triazapentalenyl (TTTA), which is known for its
photoinduced transition from the dimerized spin-singlet phase to the regular
paramagnetic phase. We conclude that the lowest photoexcited state of TTTA is
the interdimer CT exciton state and the second lowest state is the intradimer
CT exciton state.Comment: 6 pages, 6 figures, to be published in J. Phys. Soc. Jp
Virulence of Cholera Toxin Gene-Positive Vibrio cholerae Non-O1/non-O139 Strains Isolated From Environmental Water in Kolkata, India
Cholera toxin (CT)-producing Vibrio cholerae O1 and O139 cause acute diarrheal disease and are proven etiological agents of cholera epidemics and pandemics. On the other hand, V. cholerae non-O1/non-O139 are designated as non-agglutinable (NAG) vibrios and are not associated with epidemic cholera. The majority of NAG vibrios do not possess the gene for CT (ctx). In this study, we isolated three NAG strains (strains No. 1, 2, and 3) with ctx from pond water in Kolkata, India, and examined their pathogenic properties. The enterotoxicity of the three NAG strains in vivo was examined using the rabbit ileal intestinal loop test. Strain No. 1 induced the accumulation of fluid in the loop, and the volume of fluid was reduced by simultaneous administration of anti-CT antiserum into the loop. The volume of fluid in the loop caused by strains No. 2 and 3 was small and undetectable, respectively. Then, we cultured these three strains in liquid medium in vitro at two temperatures, 25 degrees C and 37 degrees C, and examined the amount of CT accumulated in the culture supernatant. CT was accumulated in the culture supernatant of strain No.1 when the strain was cultured at 25 degrees C, but that was low when cultured at 37 degrees C. The CT amount accumulated in the culture supernatants of the No. 2 and No. 3 strains was extremely low at both temperature under culture conditions examined. In order to clarify the virulence properties of these strains, genome sequences of the three strains were analyzed. The analysis showed that there was no noticeable difference among three isolates both in the genes for virulence factors and regulatory genes of ctx. However, vibrio seventh pandemic island-II (VSP-II) was retained in strain No. 1, but not in strains No. 2 or 3. Furthermore, it was revealed that the genotype of the B subunit of CT in strain No. 1 was type 1 and those of strains No. 2 and 3 were type 8. Histopathological examination showed the disappearance of villi in intestinal tissue exposed to strain No. 1. In addition, fluid accumulated in the loop due to the action of strain No. 1 had hemolytic activity. This indicated that strain No. 1 may possesses virulence factors to induce severe syndrome when the strain infects humans, and that some strains of NAG vibrio inhabiting pond water in Kolkata have already acquired virulence, which can cause illness in humans. There is a possibility that these virulent NAG vibrios, which have acquired genes encoding factors involved in virulence of V. cholerae O1, may emerge in various parts of the world and cause epidemics in the future
Random Antiferromagnetic Spin-1/2 Chains with Competing Interactions
We study disordered antiferromagnetic spin-1/2 chains with nearest- and
further-neighbor interactions using the real-space renormalization-group
method. We find that the system supports two different phases, depending on the
ratio of the strength between nearest-neighbor and further-neighbor
interactions as well the bond randomness strength. For weak further neighbor
coupling the system is in the familiar random singlet phase, while stronger
further neighbor coupling drives the system to a large spin phase similar to
that found in the study of random antiferromagnetic-ferromagnetic spin chains.
The appearance of the large spin phase in the absence of ferromagnetic coupling
is due to the frustration introduced by further neighboring couplings, and is
unique to the disordered chains.Comment: 11 pages, 7 figure
Magnetic Phase Diagram of Spin-1/2 Two-Leg Ladder with Four-Spin Ring Exchange
We study the spin-1/2 two-leg Heisenberg ladder with four-spin ring exchanges
under a magnetic field. We introduce an exact duality transformation which is
an extension of the spin-chirality duality developed previously and yields a
new self-dual surface in the parameter space. We then determine the magnetic
phase diagram using the numerical approaches of the density-matrix
renormalization-group and exact diagonalization methods. We demonstrate the
appearance of a magnetization plateau and the Tomonaga-Luttinger liquid with
dominant vector-chirality quasi-long-range order for a wide parameter regime of
strong ring exchange. A "nematic" phase, in which magnons form bound pairs and
the magnon-pairing correlation functions dominate, is also identified.Comment: 18pages, 7 figure
Electronic States and Magnetic Propertis of Edge-sharing Cu-O Chains
The electronic states and magnetic properties for the copper oxides
containing edge-sharing Cu-O chains such as LiCuO,
LaCaCuO and CuGeO are systematically studied. The
optical conductivity and the temperature dependence of the
magnetic susceptibility for single crystalline samples LiCuO
are measured as a reference system and analyzed by using the exact
diagonalization method for small Cu-O clusters. It is shown that the spectral
distribution of is different between edge-sharing and
corner-sharing Cu-O-Cu bonds. The charge transfer gap in edge-sharing chains is
larger than that of high- cuprates. The exchange interaction between
nearest-neighbor copper ions in edge-sharing chains depends sensitively
on the Cu-O-Cu bond angles. In addition to , the exchange interaction
between next-nearest-neighbor copper ions has sufficient contribution to
the magnetic properties. We calculate and for all the copper oxides
containing edge-sharing Cu-O chains and discuss the magnetic properties.Comment: 10 pages,RevTeX,8 postscript figures. Accepted for publication in
Phys. Rev.
Polaronic states with Spin-Charge-Coupled Excitation in a 1D Mott Insulator K-TCNQ
We discuss photogenerated midgap states of a one-dimensional (1D) dimerized
Mott insulator, potassium-tetracyanoquinodimethane (K-TCNQ). Two types of
phonon modes are taken into account: intermolecular and intramolecular
vibrations. We treat these phonon modes adiabatically and analyze a theoretical
model by using the density-matrix renormalization group (DMRG). Our numerical
results demonstrate that the intermolecular lattice distortion is necessary to
reproduce the photoinduced midgap absorption in K-TCNQ. We find two types of
midgap states. One is a usual polaronic state characterized by a localized
elementary excitation. The other is superposition of two types of excitations,
a doped-carrier state and a triplet-dimer state, which can be generally
observed in 1D dimerized Mott insulators, not limited to K-TCNQ.Comment: 6 pages, 8 figures, to appear in J. Phys. Soc. Jpn. Vol.77, No.7
(2008
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