190 research outputs found
Polarization and relaxation of radon
Investigations of the polarization and relaxation of Rn by spin
exchange with laser optically pumped rubidium are reported. On the order of one
million atoms per shot were collected in coated and uncoated glass cells.
Gamma-ray anisotropies were measured as a signal of the alignment (second order
moment of the polarization) resulting from the combination of polarization and
quadrupole relaxation at the cell walls. The temperature dependence over the
range 130C to 220C shows the anisotropies increasing with
increasing temperature as the ratio of the spin exchange polarization rate to
the wall relaxation rate increases faster than the rubidium polarization
decreases. Polarization relaxation rates for coated and uncoated cells are
presented. In addition, improved limits on the multipole mixing ratios of some
of the main gamma-ray transitions have been extracted. These results are
promising for electric dipole moment measurements of octupole-deformed
Rn and other isotopes, provided sufficient quantities of the rare
isotopes can be produced.Comment: 4 pages, 4 figure
Structure-property relationships of novel phosphonate-functionalized networks and gels of poly(β-amino esters)
pH sensitivity, biodegradability and high biocompatibility make poly(β-amino esters) (PBAEs) important biomaterials with many potential applications including drug and gene delivery and tissue engineering, where their degradation should be tuned to match tissue regeneration rates. Therefore, we synthesize novel phosphonate-functionalized PBAE macromers, and copolymerize them with polyethylene glycol diacrylate (PEGDA) to produce PBAE networks and gels. Degradation and mechanical properties of gels can be tuned by the chemical structure of phosphonate-functionalized macromer precursors. By changing the structure of the PBAE macromers, gels with tunable degradations of 5–97% in 2 days are obtained. Swelling of gels before/after degradation is studied, correlating with the PBAE identity. Uniaxial compression tests reveal that the extent of decrease of the gel cross-link density during degradation is much pronounced with increasing amount and hydrophilicity of the PBAE macromers. Degradation products of the gels have no significant cytotoxicity on NIH 3T3 mouse embryonic fibroblast cells
Mass Measurement of P for Improved Type-I X-ray Burst Modeling
Light curves are the primary observable of type-I x-ray bursts. Computational
x-ray burst models must match simulations to observed light curves. Most of the
error in simulated curves comes from uncertainties in process reaction
rates, which can be reduced via precision mass measurements of
neutron-deficient isotopes in the process path. We perform a precise
atomic mass measurement of P and use this new measurement to update
existing type-I x-ray burst models to produce an improved light curve.
High-precision Penning trap mass spectrometry was used to determine the
atomic mass of P. Modules for Experiments in Stellar Astrophysics (MESA)
was then used to simulate x-ray bursts using a 1D multi-zone model to produce
updated light curves. The mass excess of P was measured to be
-670.7 0.6 keV, a fourteen-fold precision increase over the mass reported
in AME2020. The Si()P and reverse photodisintegration
reaction rates have been determined to a higher precision based on the new,
high precision mass measurement of P, and MESA light curves generated
using these rates. Changes in the mass of P seem to have minimal effect
on XRB light curves, even in burster systems tailored to maximize impact.
The mass of P does not play a significant role in x-ray burst light
curves. It is important to understand that more advanced models don't just
provide more precise results, but often qualitatively different ones. This
result brings us a step closer to being able to extract stellar parameters from
individual x-ray burst observations. In addition, the Isobaric Multiplet Mass
Equation (IMME) has been validated for the quartet, but only
after including a small, theoretically predicted cubic term and utilizing an
updated excitation energy for the isobaric analogue state of Si.Comment: 8 pages, 7 figure
Stem cell transplantation for congenital dyserythropoietic anemia : an analysis from the European Society for Blood and Marrow Transplantation
Non peer reviewe
Information About Salix Matsudana
This article provides information about Salix matsudana, popularly known as willow, and also explains its structure, habitat and medicinal benefits
Energy properties of rotational bands of 170-174Yb isotopes
Accounting for Coriolis mixing of experimentally known rotational bands non-adiabatic effects in energy of low-lying excited states are investigated, within phenomenological model. The Calculations for isotopes 170,172,174,176yb, are carried out.
The energy and wave function structure of excited states are calculated. The finding reveals that the bands mixing has been found to have considerable impact on the wave function of low-lying states 0+ and 2+ bands
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