710 research outputs found
Resin composition
The invention relates to an incombustible resin composition produced by blending a compound with a specific ester bond and imide bond in a combustible resin
Out-of-phase oscillation between superfluid and thermal components for a trapped Bose condensate under oscillatory excitation
The vortex nucleation and the emergence of quantum turbulence induced by
oscillating magnetic fields, introduced by Henn E A L, et al. 2009 (Phys. Rev.
A 79, 043619) and Henn E A L, et al. 2009 (Phys. Rev. Lett. 103, 045301), left
a few open questions concerning the basic mechanisms causing those interesting
phenomena. Here, we report the experimental observation of the slosh dynamics
of a magnetically trapped Rb Bose-Einstein condensate (BEC) under the
influence of a time-varying magnetic field. We observed a clear relative
displacement in between the condensed and the thermal fraction center-of-mass.
We have identified this relative counter move as an out-of-phase oscillation
mode, which is able to produce ripples on the condensed/thermal fractions
interface. The out-of-phase mode can be included as a possible mechanism
involved in the vortex nucleation and further evolution when excited by time
dependent magnetic fields.Comment: 5 pages, 5 figures, 25 reference
Engineering a Dimeric Caspase-9: A Re-evaluation of the Induced Proximity Model for Caspase Activation
Caspases are responsible for the execution of programmed cell death (apoptosis) and must undergo proteolytic activation, in response to apoptotic stimuli, to function. The mechanism of initiator caspase activation has been generalized by the induced proximity model, which is thought to drive dimerization-mediated activation of caspases. The initiator caspase, caspase-9, exists predominantly as a monomer in solution. To examine the induced proximity model, we engineered a constitutively dimeric caspase-9 by relieving steric hindrance at the dimer interface. Crystal structure of the engineered caspase-9 closely resembles that of the wild-type (WT) caspase-9, including all relevant structural details and the asymmetric nature of two monomers. Compared to the WT caspase-9, this engineered dimer exhibits a higher level of catalytic activity in vitro and induces more efficient cell death when expressed. However, the catalytic activity of the dimeric caspase-9 is only a small fraction of that for the Apaf-1-activated caspase-9. Furthermore, in contrast to the WT caspase-9, the activity of the dimeric caspase-9 can no longer be significantly enhanced in an Apaf-1-dependent manner. These findings suggest that dimerization of caspase-9 may be qualitatively different from its activation by Apaf-1, and in conjunction with other evidence, posit an induced conformation model for the activation of initiator caspases
The study of nearest- and next-nearest-neighbour magnetic interactions in seven tetragonal compounds V(IV) containing linear chains and square lattices
A new crystal chemical method was used to calculate the sign and strength not
only of the nearest-neighbor (NN)interactions, but also of the
next-nearest-neighbor (NNN) ones in tetragonal compounds Zn2(VO)(PO4)2
(I),(VO)(H2PO4)2 (II), (VO)SiP2O8 (III), (VO)SO4 (IV), (VO)MoO4 (V),
Li2(VO)SiO4 (VI) and Li2(VO)GeO4 (VII) with similar sublattices of V4+ ions on
the basis of the room-temperature structural data. The reason for difference
between respective magnetic interactions characteristics of these compounds was
established. It is shown that the characteristic feature of these compounds is
a strong dependence of the strength of magnetic interactions and the magnetic
moments ordering type on slight displacements of XO4 (X = P, Mo, Si or Ge)
groups even without change of the crystal symmetry. In addition to extensively
studied square lattice, other specific geometrical configurations of V4+ were
discovered. These configurations can result in frustration of magnetic
interactions, namely linear chains along the c-axis with competing nearest- and
next-to-nearest-neighbor interactions; rectangular (in I) and triangular (in
II-VII) lattices with non-equivalent nearest-to-neighbor interactions, which
can be also considered as n-leg ladders; one extra square lattice in the
ab-plane with longer range interactions. It was concluded that virtually all
magnetic interactions in these compounds were frustrated.Comment: 16 pages, 5 figure, 1 table; numerous grammatical change
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