84 research outputs found
In Vitro Synthesis of Branchless Linear (1 → 6)-α-d-Glucan by Glucosyltransferase K: Mechanical and Swelling Properties of Its Hydrogels Crosslinked with Diglycidyl Ethers
A hydrogel was prepared from a polysaccharide, enzymatically synthesized through a one-pot reaction in aqueous solution, and its properties as a functional material were evaluated. Enzymatic synthesis using glucosyltransferase K obtained from Streptococcus salivarius ATCC 25975 was performed with sucrose as a substrate. The synthetic product was unbranched linear (1 → 6)-α-d-glucan with a high molecular weight, Mw: 1.0–3.0 × 105. The synthesized (1 → 6)-α-d-glucan was insoluble in water and crystallized in a monoclinic unit cell, which is consistent with the hydrated form of dextran. Transparent and highly swellable (1 → 6)-α-d-glucan hydrogels were obtained by crosslinking with diglycidyl ethers. The hydrogels showed no syneresis and no volume change during compression, resulting in the retention of shape under repeated compression. The elastic moduli of these hydrogels (<60 kPa) are smaller than those of other polysaccharide-based hydrogels having the same solid contents. The oven-dried gels could be restored to the hydrogel state with the original transparency and a recovery ratio greater than 98%. The mechanism of water diffusion into the hydrogel was investigated using the kinetic equation of Peppas. The properties of the hydrogel are impressive relative to those of other polysaccharide-based hydrogels, suggesting its potential as a functional biomaterial
Penguin Effects on K Pi and PiPi Decays of the Meson
We give the detailed analyses for the gluonic-penguin effect on the \kp and
\pp decays of the meson. In the standard model, it is shown that the
ratio BR(B\A\kp)/BR(B\A\pp) takes the value with the strongly
depending on the CP violating phase and the KM matrix element
. We obtain the constraint on the form factor by using the
experimental branching ratio. It is also found that, in the two-Higgs-doublet
model, the charged Higgs contribution which could enhance the B\A X_s\r decay
does not a sizable effect on our processes. The effect of the final state
interaction on these processes is also discussed.Comment: LATEX-file without figures. Figures will be sent by request to
[email protected]
Electric Dipole Moments of Neutron and Electron in Two-Higgs-Doublet Model with Maximal violation
We study the electric dipole moments(EDM) of the neutron and the electron in
the two-Higgs-doublet model, in the case that symmetry is violated
maximally in the neutral Higgs sector. We take account of the Weinberg's
operator O_{3g}=GG\t G as well as the operator
for the neutron, and the Barr-Zee diagrams for the electron. It is found that
the predicted neutron EDM could be considerably reduced by the destructive
contribution of the two Higgs scalars to get the lower value than the
experimental bound. As to the electron EDM, the predicted value is smaller in
one order than the experimental one.Comment: 15pages, UWThPh-1994-48, AUE-08-94, US-94-06. The post-script files
of figures will be sent by request by electric mai
Reduced N-acetylaspartate levels in mice lacking aralar, a brain- and muscle-type mitochondrial aspartate-glutamate carrier
Aralar is a mitochondrial calcium-regulated aspartate-glutamate carrier mainly distributed in brain and skeletal muscle, involved in the transport of aspartate from mitochondria to cytosol, and in the transfer of cytosolic reducing equivalents into mitochondria as a member of the malate-aspartate NADH shuttle. In the present study, we describe the characteristics of aralar-deficient (Aralar-/-) mice, generated by a gene-trap method, showing no aralar mRNA and protein, and no detectable malate-aspartate shuttle activity in skeletal muscle and brain mitochondria. Aralar-/- mice were growth-retarded, exhibited generalized tremoring, and had pronounced motor coordination defects along with an impaired myelination in the central nervous system. Analysis of lipid components showed a marked decrease in the myelin lipid galactosyl cerebroside. The content of the myelin lipid precursor, N-acetylaspartate, and that of aspartate are drastically decreased in the brain of Aralar-/- mice. The defect in N-acetylaspartate production was also observed in cell extracts from primary neuronal cultures derived from Aralar-/- mouse embryos. These results show that aralar plays an important role in myelin formation by providing aspartate for the synthesis of N-acetylaspartate in neuronal cell
TIM-1 and TIM-4 Glycoproteins Bind Phosphatidylserine and Mediate Uptake of Apoptotic Cells
SummaryThe T cell immunoglobulin mucin (TIM) proteins regulate T cell activation and tolerance. Here we showed that TIM-4 is expressed on human and mouse macrophages and dendritic cells, and both TIM-4 and TIM-1 specifically bound phosphatidylserine (PS) on the surface of apoptotic cells but not any other phospholipid tested. TIM-4+ peritoneal macrophages, TIM-1+ kidney cells, and TIM-4- or TIM-1-transfected cells efficiently phagocytosed apoptotic cells, and phagocytosis could be blocked by TIM-4 or TIM-1 monoclonal antibodies. Mutations in the unique cavity of TIM-4 eliminated PS binding and phagocytosis. TIM-4 mAbs that blocked PS binding and phagocytosis mapped to epitopes in this binding cavity. These results show that TIM-4 and TIM-1 are immunologically restricted members of the group of receptors whose recognition of PS is critical for the efficient clearance of apoptotic cells and prevention of autoimmunity
Natural Neutrino Mass Matrix
Naturalness of the neutrino mass hierarchy and mixing is studied. First we
select among 12 neutrino mixing patterns a few patterns, which could form the
natural neutrino mass matrix. Further we show that if the Dirac neutrino mass
matrix is taken as the natural one in the quark sector, then only two mixing
patterns without the large mixing lead to the natural right-handed Majorana
mass matrix. The rest of the chosen patterns with three degenerate mass
solution lead to the unnatural right-handed Majorana mass matrix in the see-saw
mechanism. Notice however, that for the chosen two natural patterns there could
be a huge mass hierarchy such as in order to reproduce
the inverse mass hierarchy of the light neutrinos.Comment: 31 pages, LaTex file, no figures, arguments made more clear, main
conclusions unchanged, version accepted for publication in PRD Reort-no:
Lund-Mph-97/14 Revise
Spontaneous CP Violation and Higgs Masses in the Next-to-Minimal Supersymmetric Model
We study the possibility of spontaneous CP violation in the next-to-minimal
supersymmetric standard model (NMSSM). It is shown that the spontaneous CP
violation is induced by the radiative effects of top, stop, bottom and sbottom
superfields. The available regions of parameters, which are obtained by
imposing the constraints from experiments, are rather narrow. We also obtain
strong constraints for light Higgs masses such as m_H \le 36 GeV numerically.
Sum of masses of two light neutral Higgs should set around 93 GeV and charged
Higgs boson has a rather higher mass larger than 700 GeV.Comment: LaTeX file, 23 pages, 3 figures, To appear in Phys.Rev.
Explicit Violation of the Higgs Sector in the Next-to-Minimal Supersymmetric Standard Model
We study the explicit violation of the Higgs sector in the minimal
supersymmetric standard model with a gauge singlet Higgs field. The magnitude
of violation is discussed in the limiting cases of and
, where and denote VEV of singlet and doublet
Higgs scalars, respectively. Our numerical predictions of the electric dipole
moments of electron and neutron lie around the present experimental upper
limits. It is found that the large violation effect reduces the magnitude
of the lightest Higgs boson mass in the order of a few ten GeV.Comment: 20 pages, LATEX, 5 figures(not included, available on request
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