81 research outputs found
How to construct a coordinate representation of a Hamiltonian operator on a torus
The dynamical system of a point particle constrained on a torus is quantized
\`a la Dirac with two kinds of coordinate systems respectively; the Cartesian
and toric coordinate systems. In the Cartesian coordinate system, it is
difficult to express momentum operators in coordinate representation owing to
the complication in structure of the commutation relations between canonical
variables. In the toric coordinate system, the commutation relations have a
simple form and their solutions in coordinate representation are easily
obtained with, furthermore, two quantum Hamiltonians turning up. A problem
comes out when the coordinate system is transformed, after quantization, from
the Cartesian to the toric coordinate system.Comment: 17 pages, LaTeX, 1 Figure included as a compressed uuencoded
postscript fil
Morphology of drawn syndiotactic polypropylene films
Morphological studies were conducted to investigate the drawability of melt-quenched (MQ) and slowly cooled (MSC) films of syndiotactic polypropylene (sPP) with a high syndiotactic pentad fraction. Transmission electron microscopy (TEM) using the ruthenium tetraoxide staining and ultrathin sectioning method revealed that amorphous chains as the matrix of MQ film played a role in drawability of the film by their alignment to machine direction (MD) and partial crystallizations into nanofibrils. On the other hand, the initial strain induced, rotations of clusters of long lamellar crystals as the major entity of MSC film accompanying breaks of long lamellae and formation of crazes and microvoids at the cluster boundary. Compared with a homogeneous thinning of MQ film by drawing, ca. 100 nm-thick layer slips along MD and parallel to the film surface took place in MSC film. This gave rise to the formation of V-shaped bent lamellar morphology and their further break into a smaller cluster of stacked lamellae which were aligned oblique by ca. 35 from MD. With elongation, some nanofibrils formed from chains generated by the partial breaks of lamellae are aligned perpendicular to the remained oblique lamellae and others parallel to MD in region where lamellar morphology almost disappeared. No chain slips in the nanofibrils can be related to a low elongation at break, i.e. a low ductility of sPP films. The lower elongation at break for MSC film than for MQ one can be interpreted by microvoids initially formed in the neck region and later moved to the fully drawn part, the microvoids initiating the break of the drawn film
Synthesis and properties of radiopaque polymer hydrogels: polyion complexes of copolymers of acrylamide derivatives having triiodophenyl and carboxyl groups and p-styrene sulfonate and polyallylamine
In order to pursue a possibility of application of radiopaque polymer hydrogels to vascular embolization, studies were done on synthesis of iodine-containing copolyanions and properties of their hydrogels with polycation via formation of polyion complexes. Acrylamide derivatives having triiodophenyl and carboxyl groups were synthesized and copolymerized with sodium styrene sulfonate at various molar ratios of initiator to monomer and temperatures. Hydrogels were prepared by mixing aqueous solutions of the obtained radiopaque copolyanions and polyallylamine. Embolization was examined by injection of these hydrogels into vein of a removed porcine kidney as a preliminary test for transcatheter arterial embolization (TAE) for hepatocellular carcinoma. It was found that the hydrogels prepared from the copolycation obtained under particular conditions give high X-ray contrasts of the vein and remained there, though copolycations with low molecular weights had a tendency to drain through the capillaries to the peripheral tissues. It is therefore concluded that the hydrogels examined in the present study are promising for vascular embolization
Site-Dilution in quasi one-dimensional antiferromagnet Sr2(Cu1-xPdx)O3: reduction of Neel Temperature and spatial distribution of ordered moment sizes
We investigate the Neel temperature of Sr2CuO3 as a function of the site
dilution at the Cu (S=1/2) sites with Pd (S=0), utilizing the muon spin
relaxation (muSR) technique. The Neel temperature, which is Tn=5.4K for the
undoped system, becomes significantly reduced for less than one percent of
doping Pd, giving a support for the previous proposal for the good
one-dimensionality. The Pd concentration dependence of the Neel temperature is
compared with a recent theoretical study (S. Eggert, I. Affleck and M.D.P.
Horton, Phys. Rev. Lett. 89, 47202 (2002)) of weakly coupled one-dimensional
antiferromagnetic chains of S=1/2 spins, and a quantitative agreement is found.
The inhomogeneity of the ordered moment sizes is characterized by the muSR time
spectra. We propose a model that the ordered moment size recovers away from the
dopant S=0 sites with a recovery length of \xi = 150-200 sites. The origin of
the finite recovery length \xi for the gapless S=1/2 antiferromagnetic chain is
compared to the estimate based on the effective staggered magnetic field from
the neighboring chains.Comment: 10 pages, 9 figures, submitted to PR
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Mesomorphic behaviour in copoly(ester-imide)s of poly(butylene-2,6-naphthalate) (PBN)
Copolycondensation of N,N’-bis(4-hydroxybutyl)-biphenyl-3,4,3',4'-tetracarboxylic diimide at 20 and 25 mol% with bis(4-hydroxybutyl)-2,6-naphthalate produces PBN-based copoly(ester-imide)s that not only crystallise but also form a (smectic) mesophase upon cooling from the melt. Incorporation of 25 mol% imide in PBN causes the glass transition temperature (measured by DSC) to rise from 51 to 74 °C, a significant increase relative to PBN. Furthermore, increased storage- (G'), loss- (G'') and elastic (E) moduli are observed for both copoly(ester-imide)s when compared to PBN itself. Structural analysis of the 20 mol% copolymer by X-ray powder and fibre diffraction, interfaced to computational modelling, suggests a crystal structure related to that of α-PBN, in space group P-1, with cell dimensions a = 4.74, b = 6.38, c = 14.45 Å, α = 106.1, β = 122.1, γ = 97.3°, ρ = 1.37 g cm-3
Multifactorial Origins of Heart and Gut Defects in nipbl-Deficient Zebrafish, a Model of Cornelia de Lange Syndrome
nipbl-deficient zebrafish provide evidence that heart and gut defects in Cornelia de Lange Syndrome are caused by combined effects of multiple gene expression changes that occur during early embryonic development
Data for: Oxygen isotope reservoirs in the outer asteroid belt inferred from oxygen isotope systematics of chondrules, isolated forsterite and olivine grains in Tagish Lake-type carbonaceous chondrites, WIS 91600 and MET 00432
Oxygen isotope and EPMA data of chondrules, isolated forsterites and olivines.
3-isotope diagrams of each chondrules
Data for: Oxygen isotope reservoirs in the outer asteroid belt inferred from oxygen isotope systematics of chondrule olivines, isolated forsterite and olivine grains in Tagish Lake-type carbonaceous chondrites, WIS 91600 and MET 00432
Oxygen isotope and EPMA data of chondrules, isolated forsterites and olivines.
3-isotope diagrams of each chondrules
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