1,412 research outputs found
Magnetoelectric Properties of (CaSr)CoSiO Crystals
We have investigated the magnetoelectric properties of
(CaSr)CoSiO () crystals with a
quasi-two-dimensional structure. In CaCoSiO (), a canted
antiferromagnetic transition occurs at 5.6 K. The transition temperature
is increasing with increasing Sr concentration, and the rises of
the magnetization and dielectric constant become larger. Since the dielectric
constant shows large change at and the magnetocapacitance effect is
observed below , a coupling between the magnetism and dielectricity
is strong in (CaSr)CoSiO. The positive
magnetocapacitance is reduced by Sr substitution, and is not observed in . Namely, the compound of does not show the
magnetic-field-induced electric polarization. On the other hand, the negative
magnetocapacitance is enhanced by Sr substitution.Comment: 4 pages, 2figures, proceeding of International Conference on
Magnetism 200
Clinical expression of plakophilin-2 mutations in familial arrhythmogenic right ventricular cardiomyopathy
Background - Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiac disorder characterized by loss of cardiomyocytes and their replacement by adipose and fibrous tissue. It is considered a disease of cell adhesion because mutations in desmosomal genes, desmoplakin and plakoglobin, have been implicated in the pathogenesis of ARVC. In a recent report, mutations in plakophilin-2, a gene highly expressed in cardiac desmosomes, have been shown to cause ARVC.Methods and Results - We investigated 100 white patients with ARVC for mutations in plakophilin-2. Nine different mutations were identified by direct sequencing in 11 cases. Five of these mutations are novel (A733fsX740, L586fsX658, V570fsX576, R413X, and P533fsX561) and predicted to cause a premature truncation of the plakophilin-2 protein. Family studies showed incomplete disease expression in mutation carriers and identified a number of individuals who would be misdiagnosed with the existing International Task Force and modified diagnostic criteria for ARVC.Conclusions - In this study, we provide new evidence that mutations in the desmosomal plakophilin-2 gene can cause ARVC. A systematic clinical evaluation of mutation carriers within families demonstrated variable phenotypic expression, even among individuals with the same mutation, and highlighted the need for a more accurate set of diagnostic criteria for ARVC
Natural cellulose coated dispersions: new opportunities in green process engineering and applications
Our recent discoveries have shown that cellulose chains could be molecularly dissolved in a solvent mixture of an ionic liquid with certain polar organic solvents, forming true solutions. Due to their molecular dissolution, the cellulose chains in hydrogels, formed by regeneration of these solutions, are also maintained in an amorphous structure. Furthermore, as was reported recently, cellulose solutions in other solvents, as well as suspensions of cellulose hydrogel particles, can be used as a novel amphiphilic coating for oil/water emulsification, by utilizing cellulose as an encapsulating agent that forms a stabilizing coating in oil-in-water and water-in-oil emulsions without the use of additional surfactants. Our innovative encapsulation process is cheap, “green” and uses simple fabrication methods (1-5).
We have studied cellulose dissolution, formation and structure of regenerated cellulose hydrogels and fragmented hydrogel dispersions. Furthermore, we studied the influence of fabrication processes on structural parameters of cellulose coated oil-in-water emulsions, as well as their enzymatic degradation.
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Anomalous Coexistence of Ferroelectric Phases ( and ) in Orthorhombic EuYMnO () Crystals
We have investigated the magnetic and dielectric properties of orthorhombic
EuYMnO () single crystals without the presence
of the 4 magnetic moments of the rare-earth ions. In , the
magnetic-structure driven ferroelectricity is observed. The ferroelectric
transition temperature is steeply reducing with increasing . In , two ferroelectric phases ( and ) are
coexistent at low temperatures. In these phases, ferroelectricity has different
origin, which is evidenced by the distinctive poling-electric-field dependence
of electric polarization. Namely, the electric polarization along the c axis
() is easily saturated by a poling electric field, therefore is
caused by the spiral antiferromagnetic order. On the other hand, the
electric polarization along the a axis () is probably attributed to the
collinear -type antiferromagnetic order, because is unsaturated even
in a poling field of V/m.Comment: 10 pages, 4figures, to be published in Journal of the Physical
Society of Japa
Persistent and Reversible Phase Control in GdMnO near the Phase Boundary
We have investigated temperature and magnetic-field dependence of dielectric
properties in the orthorhombic GdMnO single crystal which is located near
the phase boundary between the ferroelectric/spiral-antiferromagnetic phase and
the paraelectric/-type-antiferromagnetic one. In this compound, strong phase
competition between these two phases results in a unique phase diagram with
large temperature and magnetic-field hystereses. Based on the phase diagram, we
have successfully demonstrated the persistent and reversible phase switching
between them by application of magnetic fields.Comment: 4 pages, 2 figures, proceeding of 25th International Conference on
Low Temperature Physics LT2
Split transplantation of the trachea: A new operative procedure for extended tracheal resection
AbstractBefore tracheal transplantation can be applied clinically, several problems must be solved: immunosuppression, blood supply to grafts, and reliable long-term preservation of grafts. We have conducted experiments on tracheal transplantation to solve these problems. In the present study, we tried a new operative procedure to accomplish reliable revascularization of transplanted tracheal grafts. It has been reported that transplantation of a 10-ring length of trachea is difficult even with omentopexy. Long tracheal allografts can be transplanted with use of direct revascularization, but this technique is extremely troublesome. Thus we developed a new operative procedure, “split tracheal transplantation,” in which grafts are divided at the midportion and covered with omentum, after demonstrating that the blood supply to tracheal grafts can be reestablished around the suture lines. Two groups of dogs were used. In group A (control, n = 4), a 10-ring length of trachea was autotransplanted. The anastomotic sites and grafts were covered with omental pedicles. In group B (split tracheal transplantation, n = 10), tracheal grafts 10 rings long were autotransplanted. These grafts were divided at the midportion, a piece of omentum was inserted between the two halves, and the midportion was sutured. Grafts were observed regularly by bronchoscopy and examined histopathologically after the animals died or were killed. In some animals, microangiography of the bronchial circulation was done. In the control group, necrosis, stenosis, or malacia of the grafts was observed in three of the four animals. In the split transplantation group, all animals survived for at least 2 months, all grafts were incorporated, and none showed ischemia, stenosis, or malacia. Microscopic examination and microangiography revealed that neovascularization of the graft was promoted by omentum inserted at the midportion of the graft. Split transplantation of the trachea is an easy and reliable way to extend tracheal resection. (J Thorac Cardiovasc Surg 1996;112:-8
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Photoactivatable genetically encoded calcium indicators for targeted neuronal imaging.
Circuit mapping requires knowledge of both structural and functional connectivity between cells. Although optical tools have been made to assess either the morphology and projections of neurons or their activity and functional connections, few probes integrate this information. We have generated a family of photoactivatable genetically encoded Ca(2+) indicators that combines attributes of high-contrast photolabeling with high-sensitivity Ca(2+) detection in a single-color protein sensor. We demonstrated in cultured neurons and in fruit fly and zebrafish larvae how single cells could be selected out of dense populations for visualization of morphology and high signal-to-noise measurements of activity, synaptic transmission and connectivity. Our design strategy is transferrable to other sensors based on circularly permutated GFP (cpGFP)
Fluorescence Imaging and Spectroscopy of Biomaterials in Air and Liquid by Scanning Near-Field Optical/Atomic Force Microscopy
We have developed scanning near-field optical/atomic force microscopy (SNOM/AFM). The SNOM/AFM uses a bent optical fiber simultaneously as a dynamic force AFM cantilever and a SNOM probe. Resonant frequency of the optical fiber cantilever is 15-40 kHz. Optical resolution of the SNOM/AFM images shows less than 50 nm. The SNOM/ AFM system contains photon counting system and polychrometer/intensified coupled charge devise (ICCD) system to observe fluorescence image and spectrograph of micro areas, respectively. Cultured cells were stained with fluorescein isothiocyanate (FITC)-labeled anti-keratin antibody or FITC-labeled phalloidin after treatment with Triton X-100. Fluorescence and topographic images were obtained in air and water. The fluorescence images showed clear images of keratin and actin filaments. The SNOM/AFM is perfect to observe biomaterials in liquid with a liquid chamber while the topographic Images showed subcellular structures which correspond to keratin and actin filaments
The ortho-to-para ratio of ammonia in the L1157 outflow
We have measured the ortho-to-para ratio of ammonia in the blueshifted gas of
the L1157 outflow by observing the six metastable inversion lines from (J, K) =
(1, 1) to (6, 6). The highly excited (5, 5) and (6, 6) lines were first
detected in the low-mass star forming regions. The rotational temperature
derived from the ratio of four transition lines from (3, 3) to (6, 6) is
130-140 K, suggesting that the blueshifted gas is heated by a factor of ~10 as
compared to the quiescent gas. The ortho-to-para ratio of the NH3 molecules in
the blueshifted gas is estimated to be 1.3--1.7, which is higher than the
statistical equilibrium value. This ratio provides us with evidence that the
NH3 molecules have been evaporated from dust grains with the formation
temperature between 18 and 25 K. It is most likely that the NH3 molecules on
dust grains have been released into the gas phase through the passage of strong
shock waves produced by the outflow. Such a scenario is supported by the fact
that the ammonia abundance in the blueshifted gas is enhanced by a factor of ~5
with respect to the dense quiescent gas.Comment: 16 pages, including 3 PS figures. To appear in the ApJ (Letters).
aastex macro
Strange filamentary structures ("fireballs") around a merger galaxy in the Coma cluster of galaxies
We found an unusual complex of narrow blue filaments, bright blue knots, and
H-alpha emitting filaments and clouds, which morphologically resembled a
complex of ``fireballs,'' extending up to 80 kpc south from an E+A galaxy RB199
in the Coma cluster. The galaxy has a highly disturbed morphology indicative of
a galaxy--galaxy merger remnant. The narrow blue filaments extend in straight
shapes toward the south from the galaxy, and several bright blue knots are
located at the southern ends of the filaments. The Rc band absolute magnitudes,
half light radii and estimated masses of the bright knots are -12 - -13 mag,
200 - 300 pc and 10^6-7 Msolar, respectively. Long, narrow H-alpha emitting
filaments are connected at the south edge of the knots. The average color of
the fireballs is B - Rc = 0.5, which is bluer than RB199 (B - R = 0.99),
suggesting that most of the stars in the fireballs were formed within several
times 10^8 yr. The narrow blue filaments exhibit almost no H-alpha emission.
Strong H-alpha and UV emission appear in the bright knots. These
characteristics indicate that star formation recently ceased in the blue
filaments and now continues in the bright knots. The gas stripped by some
mechanism from the disk of RB199 may be traveling in the intergalactic space,
forming stars left along its trajectory. The most plausible fireball formation
mechanism is ram pressure stripping by high-speed collision between the galaxy
and the hot intra-cluster medium. The fireballs may be a snapshot of diffuse
intra-cluster population formation, or halo star population formation in a
cluster galaxy.Comment: 13 pages, 14 figures, submitted to Ap
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